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The magazine recently purchased a 2000 Honda XR650R motorcycle with less than 1000 original miles on the bike. An honest and forthright previous owner could not start the engine, and given the mileage, we agreed that the problem was stale winter (ethanol) fuel—which had eaten up the plastic tank screen! I trailered the cycle home and looked forward to restoring the fuel system and completing the dual-sport conversion process. The motorcycle will be an HD video shooting platform for remote backcountry documentary filming and off-pavement event coverage, so the XR650R's low mileage seemed a huge asset.

After 20 hours of prepping the cycle for a Nevada dual-sport inspection, including some minor tuning and checking out the bike's general condition, I discovered that the 650 thumper engine would not start. Consulting two friends with XR650Rs, I assumed that my starting technique was the culprit. A heavy cardio workout later, it was apparent that the compression was lacking. I did a quick compression gauge check and discovered a 95 PSI cranking compression issue. (To assure an accurate reading, make sure the auto-decompression mechanism is not holding the valves open when performing a compression test!)

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My next step was a cylinder leak down test, which I have covered in detail with an HD video how-to feature. All of this is covered in a series of HD videos available at my YouTube channel and the motorcycle Playlist.  (Go to https://www.youtube.com/c/roadreadywithmosesludel and open the XR Honda motorcycle playlist.)  The leak down test pinpointed leaking intake and exhaust valves; a look inside the cylinder (through the spark plug hole) also indicated scoring at the upper wall of the Nikasil cylinder plating. Time for an upper engine tear down, which I cover as a step-by-step HD video at the YouTube Playlist.

So, how did a "bulletproof" Honda XR650R motorcycle, with less than 1000 miles since new, end up with a worn out set of valves and leaky piston and rings? The answer is two-fold: 1) the motorcycle had an incomplete "uncorking" job with a partial "Honda Power-Up Kit" installed and 2) a leaking aftermarket air filter had seeped abrasive dirt into the air stream and through the engine's intake system. The air filter issue is notorious for pitting valves, scoring an upper cylinder and damaging piston rings on motorcycle and automotive engines. An incomplete uncorking calls attention to an ever important problem for any motorcycle engine modification: the need to re-jet the carburetor to compensate for improved intake flow or a less restrictive exhaust system!

The "Power-Up Kit" opened up the exhaust cap on the muffler and reduced exhaust backpressure (basically an HRC end cap). The cycle is a non-California model, so there was no restrictive "D" molding in the intake manifold grommet. (The non-California intake manifold is considered the unrestricted air intake, often sold as the upgrade for better breathing.) The pilot jet had the Power Up Kit's #68 sizing, though not the specific "68s" style. However, for some unfathomable reason, the main jet in place was still the ultra-lean, original 125 main jet!  The most important ingredient in the uncorking process for a Honda XR650R motorcycle engine is the unrestricted rubber intake manifold and a jetting change to a 175 main jet and 68s pilot jet (base line at sea level). Exhaust modifications help further, the stock OE muffler's exit flow and end cap are ridiculously small for a 650 thumper!

How important is the 175 main jet and 68s pilot? Important enough to be the OEM jet sizing on all Honda XR650R engines sold outside of North America! The U.S. engines were leaned to the limit by E.P.A. requirements, and California models (XR650R AC designation) were even more restricted by a draconian reshape and air flow restriction in the rubber intake manifold and the intake air box. So, this uncorked, non-California model had its exhaust opened and uncapped—plus the removal of air intake box restrictors. The EPA regulated (non-California) cycle already had the open, round intake manifold. It was in severe need of the 175 main jet, however, which the dealer neglected to install with the power tuning!

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The result is clear. Despite the low mileage, this engine was busy overheating its upper cylinder and valves. Upon tear down, which you can follow in the HD video linked above, the engine's upper cylinder looked more like a Baja 1000 Race finisher than 1000 miles of reasonable recreational riding. Fortunately, the previous owner had used quality lubricant and changed oil filters regularly. The XR650R's unique liquid cooling (the only XR to ever offer it!) also helped minimize damage and isolate the wear to the cylinder plating, piston skirts, rings and valves. The main engine assembly is still in near-new condition.

I'm now in the process of rebuilding the upper engine. The head and cylinder have been sublet to L.A. Sleeve Company. My approach will likely be an alloy iron/chrome/moly, patented L.A. Sleeve liner in place of the factory Nikasil. Though many are fans of Nikasil, I'm not thrilled that's its only a "plating" thick. This Honda XR650R has a lot of work ahead, and it must be ultra reliable.

I may consider a Stage 1 Hot Cams alternative, mainly to eliminate the auto-decompression mechanism on the OE camshaft. Compression ratio will remain the stock 10:1 with the new upgrade piston, enough squeeze for higher altitudes and the limit for kick starting and long piston ring life! Quality machine work, a fresh cylinder and upgrade piston choice, renewed valves and proper assembly technique will have this motorcycle living up to its legendary reputation—with a 175 main jet and 68* pilot jet in its Keihin carburetor!  Follow the rebuild how-to coverage at the in 1080P HD video at the "Road Ready with Moses Ludel" YouTube channel!

*Note: The carburetor now has a straight 68 jet installed, and I will see if the 68s is necessary. There is a difference in the flow between these two varieties. Honda's Power-Up Kit does call for the 68s and also a needle change if necessary. I may need to fine tune further for northern Nevada and the Sierra. Our home base is 4,100 feet elevation and high desert; the average/mean elevation at Nevada is 5,500 feet. I did drop the 175 main jet down to a 172, a slight compromise for our local altitude and runs. I can still run the bike from sea level to 7,000 feet with this main jet although from 4000-7000 feet, the carburetor and engine run progressively richer.  The XR650R engine can "tolerate" this rich mix for brief runs.  Ideally, I would rejet for each 1000 feet of elevation change.  I use Sea Foam Motor Treatment in the fuel to keep the upper engine clean and watch both the spark plug and tailpipe coloration closely.

Moses

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very interesting stuff moses.   my 650 was already uncorked and unplugged when i bought it, so i have no idea about condition or jetting, etc.  the manual start is a real bugger.  sometimes i get pretty winded just getting it to start, not counting all the times right foot slips off kick start lever  and right foot peg jams into the shin...ouch.  that said, it can sit for months and months and after about 7-8 good kicks, starts right up.  My latest project is to install the front brake re build kit.  seems sitting for a length of time allows air to get sucked into the system leading to no or nearly no front brake.  yikes!  tired of constant bleeding.

 

in other news, took delivery of the uber-cool dual voltage gauge for jeep.  the instructions show it simply hooked direct to the batteries, but i am concerned parasitic draw may pull down those batteries.    will advise and best to all in the new year.

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RareCj8...A leak down test is spot on and conclusive (see HD video for details). The damage source for my engine was clear when I discovered the 125 OEM main jet in place and dirt around the edge of the air filter.  This cycle had been ridden primarily in Texas (lower elevations) on the lean mixture.

 

Generally understood is that "uncorking" involves a list of changes, which includes the 175 main jet (selection is a no brainer, this is the OE main jet outside the U.S. for engines identical to ours). All of the XR650Rs with the OE main jet are under duress, especially non-California models still running with the original main jet. Uncorking without changing the main and pilot jets becomes the death knell. Here is the "official" Honda Power-Up Kit list of parts plus the removal of the air box restrictors. (This list is third party info and somewhat dated; confirm current part numbers available at your Honda dealership.) The list:

 

 16211-MBN-640 (Insulator, Carburetor, which gets rid of the California "D" shaped restrictor manifold)
 18317-MBN-640 (Exhaust Tip without the tiny outlet and restriction)
 99105-MBN-0680 (68s Pilot Jet)
 99101-357-1750 (Main Jet 175)
 16012-MBN-641 (B53E Needle Set, this is based on tuning needs; at our altitude, try without the needle change first)

 

Also expected is the removal of the "user removable" air box restrictions. A Power Up Kit should not be confused with the Honda Racing kit for the XR650R. The HRC kit adds a warmer camshaft, improved piston and rings with bumped compression (11:1, really?) plus other racing nuances.

 

The OE Keihin pilot and main jet are each accessible with the float bowl removed, and the Keihin carburetor can be carefully rotated to access all four float bowl screws. They are Japanese Phillips head and vulnerable to rounding if not careful, but most of us who have owned Japanese motorcycles have been there and own a hand impact driver for that purpose. 

 

You can access and remove the main jet by simply unscrewing the drain plug at the bottom of the float bowl and accessing the jet with an appropriate 1/4" drive metric socket. This lean issue is serious enough to warrant looking at the installed jet if you're unsure of its size/flow. You and I live at nearly the same altitude, and I opted for a 172 main jet for the 4,500-7,000 foot elevation range that I typically ride. 175 would likely be okay if you want to play it safe for sea level, you should be able to readily run to 6,000 or so feet without fouling a spark plug. When you read the jet change charts, even from Honda, there's a wide range of adjustment for ambient temperature and altitude. My cycle's pilot had been changed to a 68 (not 68s), which I'll try and go from there. I haven't pursued the needle position or type, would bet it's stone stock since the carburetor's top looks unopened. We can discuss fine tuning and carburetor staging later...For others, keep in mind that tuning is altitude and temperature sensitive.

 

As for the voltage meter(s) for the CJ-8 Jeep, I totally agree. We're back to my suggestion that you simply route the lead wire to the voltmeter through a standard Bosch-type relay that is key-on activated. The relay would close the circuit on the wire lead when you turn on the ignition key and open the circuit/lead when you turn off the key. This would deactivate current flow of any kind with the key off. Refer to my primitive drawing (earlier exchange) for ideas.

 

Have a safe and very Happy New Year! We'll ride the Big Red Pigs (XR650s) at the desert when I get this beast plated, I'm looking forward to that prospect!

 

Moses

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  • 6 months later...

Hi Moses, have you got an idea about what jets and needles the Euro version of the XR would have come with stock? I'm going to open my carb for maintenance and will be doing some thinking about what should or shouldn't be in there. As you know, my motor (Euro model) is fried from overheating/dirt ingestion/bad maintenance...

 

D.

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  • 4 weeks later...
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Hi, David...I've been very busy with Michelin T63 tire testing on the Honda XR650R, you'll enjoy the road testing and also the addition of TCI Products racks and Nelson-Rigg bags...

 

As for jetting, here is a PDF with Euro and Australia specifications:

 

Honda XR650R Specifications.pdf

 

You should have a 175 main jet, a 65 pilot jet and the needle clip in the third groove from the top.  You'll see this listed by market in the specs.  Also, I included many of the other detail specs that you might find useful to your project.

 

Thanks for posting, I'm back from the tests and HD video filming, so my responses will be timely.  You'll get a real kick out of the off-pavement and on-pavement testing.  Stay tuned, I'll be doing the post production video edit work this week!

 

Moses

 

 

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Hi Moses,

 

I've now had a chance to go through the posts - thanks for the responses! The spec sheet is gonna come in very handy!

 

As far as jetting is concerned, I may have mentioned that I ordered a Moose Racing repair kit off a French website, hoping it would have the correct jets in it. Although the kit came with the 65 pilot, it does not have the 175 main in it (I think it was a 150 or less). So I have gone to HondaParts-Direct and ordered the 175 which I will receive here in the US (I arrived yesterday) to take back with me.

 

But I was just wondering - in other words I'm asking for input :) - about jetting. The higher the number on the jet in this case, the more fuel it's flowing, right? And the higher the altitude, the less fuel you want flowing (to maintain the right air/fuel ratio), right? Same goes for when it's hotter, right? If so, this leads me to believe that for my application at 3,000-6,000 ft. in average daytime temps of about 80 Fahrenheit, I should go leaner than 175. Anyway, when I open the carb, I'll see what was in it originally and take it from there.

 

One problem I'm going to have to deal with is a seized mixture screw (the one that goes horizontally into the carb body). Not only is it seized but there's not much of a head left on it - and it's recessed into a hole of sorts, making it impossible to grab with a pair of pliers... So I don't have any bright ideas on how to get it out - much less how to adjust it! If I knew what it was set at (how many turns out), I could just leave it alone, but I doubt that it is adjusted correctly. Phooey.

 

D.

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You're right about jet numbers and sizing, David.  We're based at 4,300 feet elevation, and most of my riding is between 4,000-7,000 feet elevation.  A 175 main jet is for sea level.  Typically, you would gradually taper down, proportionately, especially for altitudes above 5,000 foot range.  Ambient temperature is also a critical factor, so pay close attention to both altitude and temperature!

 

I've attached an older Honda workshop recommendation for my 1984 Honda XR350R that should clarify the goals here.  (The later manuals are remiss about much of this logic, apparently too busy appeasing exhaust emission regulatory agencies.)  1984 was still an era when getting a dirt motorcycle engine to run right and last a long time held priority.  Disregard the XR350R model-specific info, you're interested in the chart and the explanation of how to use the chart and do the math, which is actually quite simple:

 

Honda Carburetor Jetting for Altitude.pdf

 

In the real world, I'm loading my bike with gear.  Just added TCI Products racks and skid protection with Nelson-Rigg bags, check out the magazine article and HD videos.  I can find myself riding at the lower desert around Moab and Southern California events.  (The Moab Area can provide a range of 4,000-6500 feet, possibly more at the La Sal Range.)  My XR650R carries added weight and will soon have a larger fuel tank, too.  I also have the Hot Cams Stage 1 camshaft, which eliminates the auto-decompression start mechanism on the stock camshaft and has been an absolute joy in real world riding gains.

 

All of that said, I strive for a balance here, plus realism about not having to change jets every time I go somewhere.  For the main jet, I opted for a 172.  For the pilot, I intentionally installed the less efficient straight 68 (not a 68S).  I get the flow rate but not the "better emulsified" fuel.  The needle clip is 3rd position from top.  The engine is faithfully and thoroughly "uncorked" to Honda 'Power-Up Kit' standards as well.  I had to complete this upgrade, as the previous owner did not, and the engine was suffering prior to the top end rebuild.  Your European market engine (stock) should have each of these modifications in its original form.  We can confirm.  Here is the Honda "factory" N.A. Power-Up Kit (not the all-out racing HRC kit) parts list:

 

Honda Factory Power Up Kit Part Numbers.txt

 

Why did I start with these specs?  My reasoning: I'm not going to change jets for Moab, Utah (4,025 feet in town) or King of the Hammers at Johnson Valley, CA (2,300-4,600 feet elevation range).  The 172 is conservative, slightly lean from a 175, rich enough for running at sea level without risk of holing a piston.  (Much more considerate than Honda's draconian 125 main jet in North American engines, detuning the engine just to run with this ridiculously lean jet!)  So, the remaining question is higher altitudes, and here's my experience to date.  Accept this as my experience and equipment.

 

The engine runs very strongly from idle to redline, without blubber, hesitation or anything other than a fast ride.  (See my Michelin road test 'Part 2' video for living proof.)  It pulls incredibly well, with excellent transitions from curb idle through midrange to redline.  The spark plug color looks great, a very good indicator of a single cylinder motorcycle engine's combustion process and air/fuel ratio

 

As for starting, first let me emphasize that I use the manual compression release lever.  Here's my approach:

 

1) I bring the piston to compression pressure (leading to TDC), then pull in the release lever and push over TDC just slightly with the kick starter before attempting to kick down.

 

2) Over TDC slightly, I firmly kick through (not with extreme force other than to overcome the needs of a 10:1 compression engine).  I can get the engine to start most often on the first or second kick, at worst, the third kick.

 

3) Here is the capper:  I avoid use of heavy choking.  If completely cold, I either place the choke on half-choke or full choke for just a few kicks with the ignition turned off and compression release lever pulled in. 

 

5) The throttle stays closed until actual engine firing, then gets blipped slightly, immediately, to let the engine breath and keep running. If cold-blooded, the throttle is held slightly open to let the engine stabilize. 

 

4) If I fire the engine with the choke on full, it must immediately be stepped down to middle position or even off (warm ambient temps now around 75 degrees F when I start the bike).  For a hardcore, subfreezing Nevada winter at 4,300 feet, I anticipate playing up the choke enrichment. 

 

5) As soon as the engine is running, I open the choke lever fully.  If I happen to get overly zealous with the choke and create a hard start or stall upon starting, I turn off the ignition, pull in the compression release lever, hold the throttle well open, and kick through 4-5 times to clean out the cylinder.  Then I start over again.

 

This starting thing for the XR650R is apparently an issue.  Many follow elaborate regimens to get the engine to fire.  Personally, I believe they must be over-fueling or over-choking the engine.  Choke opened immediately, I can get my engine to idle stably within a 1/4- to 1/2-mile of riding this time of year. 

 

I do exert caution when the engine is cold while riding with the choke open.  The engine is lean, and I can feel it wanting slightly more fuel, which I provide with throttle instead of the choke. 

 

Keep in mind that the main jet size has virtually no impact on idle.  The pilot jet does, however, and it also affects the lower speed throttle transitions.  Of course, the idle mixture screw circuit has the largest impact with the stock carburetor design.  I must say that other than the idle speed when cold with the choke completely off, my engine responds wonderfully, both hot and cold. 

 

I compensate for the open choke until the engine warms.  This is just my approach, I don't like over-fueling the engine during its warm-up cycle.  Some don't mind.  The tip-off for me is that the bike can be immediately ridden with the choke off, without hesitating, faltering or stalling—as long as I work the throttle slightly when coming to a complete stop and idle.

 

You may need or benefit from a leaner main jet at your altitude and engine tune, but this can only be tested at higher rpm with the engine's performance under open throttle.  Lower speeds, you're more concerned with the pilot, and a 65, which is stock for North America, apparently is all Moose can provide.  Sounds like they're emission constrained and not into the "Honda Power Up" kit approach, which is readily available through dealerships as "off-highway" use as you discovered. This is Catch-22, since the N.A. bike was not authorized for highway use, according to California and EPA, yet you can jet for better off-highway performance!  And Honda is the guideline we use here, its Power-Up Kit part numbers include the 175 main, 68(S) pilot and the change in needle and seat.

 

The needle and seat change is not as crucial as the needle position, which should be 3rd clip position (from the top) for starters.  This is an easy road test, as the transitions from a closed to open throttle, including abrupt throttle changes, will indicate the correctness or shortfalls of the pilot jet size and needle position.  We can talk about this when you get the bike on the road. 

 

For me, I took an educated guess and accounted for the improved breathing of the Power-Up part numbers, including the exhaust tip which you can see in the Nelson-Rigg/TCI Products coverage, and my camshaft change.  I have the non-California, round inside intake grommet between the carburetor and the cylinder head, too.  This was stock, as the bike, fortunately, was original sold in Texas.  I have none of the California emissions pump paraphernalia, which pops up in distinctions between the XR650A and XR650AC parts listings. 

 

AC is a California designated engine that deserves great sympathy.  When you have the time on one of your online searches for part numbers, check out the distinctions and schematics for the AC versus straight A models.  Here are the primary pieces you should not find on your European XR650R (not OEM on my cycle, either, fortunately) that California buyers will be chasing down for years to come: http://www.hondapartshouse.com/oemparts/a/hon/5053e96bf870021c54be3708/air-suction-valve-ac

 

The other key AC pieces were the extreme exhaust tip restriction, narrowed passage intake grommet, restricted air box and jetting restrictions.  Some of these items carry over to the "A" models as well.  After the complete 'Power-Up Kit' upgrade, my engine is like yours should be, with the stock, non-California round type intake grommet, larger exhaust tip piping, unrestricted air box (yours might have the restrictors still) and proper jetting.  You might share photos of your stock Euro equipment.  N.A. members and guests would find that interesting.

 

I am very curious what your stock jetting turns out to be, including the main and pilot plus the needle clip position.  A light rebuild is a wonderful treat for these carburetors, and judging by your idle mixture screw, perhaps you'll be lucky, and nobody damaged the rest of the carburetor.  The idle screw is readily available, on my used model that was an item I replaced.  The very fine tip needs extreme care when installing the screw.  If off-center, that tip will bend in a wink.  Do not force the screw into position, you'd be guaranteed trouble!  When you remove the idle mixture screw, the tip size will be clear.

 

As for removing the damaged screw, there are several approaches here.  Since you'll have the carburetor off anyway, you can carefully drill the center of the screw head with a smaller bit. If you have a drill motor than can be reversed, a left hand drill bit will often spin a screw loose while you're attempting to drill the hole.  If not, use care not to damage the threaded portion of the carburetor body, and spend some time with a drill and tiny easy-out, removing the mixture screw once you can get the easy-out into the drilled hole.

 

Let's keep this discussion going.  I'd like to know your findings, your conclusions and your experience with both the jetting and the starting technique.  I don't believe that any properly tuned engine should be "hard to start".  These engines are sensitive only due to one cylinder and lots of compression.  Make friends with your engine's particular starting preferences.  Mine work for me, I can start the engine cold or hot on one to three kicks maximum.  That's actually better than the Baja racing versions of these engines. 

 

My favorite cult classic XR650R movie, "Dust to Glory", shows how race positions actually change during a pit restart.  Andy Grider has just outpaced Johnny Campbell in an epic battle between pits and hands over his bike to the next Honda B Team rider.  The B Team rider can't get the XR650R to fire promptly, and the A Team rider sails by...Good tale about the XR650R and hard starting, but don't let this get you down.  With proper tuning and conservative use of the choke, anyone can share my experience.

 

Note: As for starting thumper motorcycles, this XR650R is not my first rodeo.  I teethed on a '69 BSA Victor 441 and owned three Honda XR enduro bikes prior to the XR650R.  Granted, the XR650R is the beast of the bunch, yet starting the engine should be the least of the rider's challenges.

 

As for setting the idle screw, 1-1/2 to 1-3/4 turns from lightly seated is a nice place to start at your altitude.  Give that a go, you'll make fine adjustment with the engine completely warmed.  Again, I go for just enough enrichment for a very smooth and stable idle, nothing more or less.  I've only touched the mixture screw one time since initial adjustment.  Here is the factory procedure, your best guideline:

 

Honda XR650R Idle Mix Setting.pdf 

 

Many owners like to fiddle endlessly with the idle speed screw, adjusting it up and down regularly.  I stopped following this myth by concentrating on stabilizing the engine with the hand throttle on the extremely rare occasions when the engine seems hesitant to idle.  Create stability by using your hand throttle, gently blipping (no major rpm changes, please, this is not a premix two-stroke!) or holding steady at a slightly higher rpm than curb idle for a moment—until the engine cleans out and temperatures stabilize.  With steady air and fuel flow, and coolant temperature stability, the XR650R will want to idle smoothly again—even with its stock ignition and OE carburetor.

 

As you gain confidence in the engine, its tune and your skillful carburetor rebuild and adjustment, this will get easier.  If you set the carburetor to factory recommendations in each area, including float height, you should have a much less finicky engine.  Don't race off to buy a $700 replacement carburetor just yet!

 

Moses

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Hi Moses, I subscribed once I read your posts in this thread. I'm sorry to read about your misfortune with your xr650r. I just bought an 2000 XR650r a couple of days ago, I have no prior experience with them. I'm an old rider, I too used to ride a BSA B50 and have a 1982 XR500r and a 1984 XR350R. I've been trying to figure out if my bike has been "uncorked" as they call it. The prior owner knew nothing about any mods. The exhaust is not restricted. I pulled the main jet and it is a 145RD. The prior owner was satisfied with the performance, none of his friends could keep up with him. The rear sprocket was changed to lower the gearing for trails, so it probably was not ridden at WOT too much. That is what I'm hoping. Before I started the bike when I got it home I found the air filter leaking dust, so I have not ridden it yet. The rubber boot was still in the airbox but the plastic is not. While the filter is being shipped I have delved into the uncorking of my bike or lack thereof. Until I read your post I could not find anything definite about the stock jetting. The Moose kit has raised my brow as to the 145RD jet in mine. I just pulled the carb and there is no restriction in the manifold. This bike was sold new in Seattle. When my jets arrive I'll disassemble the carb and see what else is in there. Thanks for your informative post. I hope other xr650r owners will post what they found in their bikes before they "uncorked" their BRP.

 

Greg

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Hi, fullchoke...We do have a lot in common!  Wow, what are the odds, we each had BSA singles and XR350R and 500R models.  Each of my air-cooled XRs are 1984 models.  We sold the '83 XR200R when our youngest son went to college in 1999 or would otherwise still have it, too.  He's coming around to dirt riding again, and we recently found him a buy on a 2003 XR400R, 134 actual miles on the odometer, essentially a brand new bike!

 

Thanks for your concern about the work I needed to do on the XR650R.  The previous owner was quite fair, there was relief for the expenses I encountered, and frankly, I'm now pleased that the top-end rebuild is done.  As strong as these bikes run, I'm sure many could be on their last leg and still "feel good".  The top engine rebuild with low overall mileage on the bike is good.  The places I ride and plan to use the bike, the loads planned, there will be no guesswork about the condition of the engine.  I have always done my own engine work, which should not surprise anyone, and the collaboration with L.A. Sleeve Company on the machine work was assurance that I have a fresh and very reliable machine!

 

As for your wonderful new acquisition, and you will be thrilled before this is done, the guideline I follow is the factory Honda "Power-Up Kit".  This is actually tuning the bike to the European and other market standards.  I did not pull my tuning specs out of thin air, instead doing my homework and even acquiring a non-North America shop manual copy to verify my findings.  The post above with the official carb jetting specs PDF is from the non-N.A. manual.

 

From this non-U.S. manual, we can glean that the basic engine is exactly the same throughout the world.  (I researched the compression, cam timing, ignition and other key features to confirm.)  The tune differs in various markets, though.  In fact, there is a different carburetor model used in Australia that has a radically smaller main jet (112#).  If the PE78D Australian carburetor has the same throat/bore opening and air flow as the PE78C (other export markets other than U.S./N.A), this Australian bike has been severely detuned.

 

For those curious, the U.S. replacement carburetor is a PE78A.  There were originally two non-California (XR650R A) part numbers and one for the California XR650R AC models, each a PE78A type Keihin carburetor.  Keep in mind, the U.S./N.A. XR650R was originally for off-highway only use, an enduro motorcycle without street use equipment.

 

This Australian market bike is actually geared for asphalt highways at 41/15 sprocket gearing and comes with a complement of lighting, directional signals, chain guard and mirrors, more like the XR650L although we can assume there are no other similarities with the air-cooled XR650L model.  I'm encouraging an Australian XR650R bike owner to jump in here to confirm that the Down Under XR650R is otherwise a true Honda XR650R.  For those curious, here are the model distinctions for Honda XR650R models sold in markets outside the U.S. or North America:

 

Honda XR650R Markets.bmp Honda Euro and Australian XR650R Models.bmp Honda XR650R Carburetor Tuning.bmp

 

"Uncorked" is the parts list I've furnished in the above threads at this topic.  These part numbers have been available through Honda motorcycle dealerships and online official Honda parts suppliers.  The 175 main jet is standard for sea level on this engine everywhere in the world except North America and Australia.  The compression ratio of 10:1 justifies the 175 main jet for full performance.  That this 649cc engine will run on the 145 (aftermarket), 125 (N.A.) or even the 112 main jet at Australia, is a testimonial to the engine's stamina and flexibility.  A 125 or 112 main jet with a carburetor bore like this and 649cc engine displacement, sounds like a piston hole looking for a place to happen!

 

Like your bike, my engine had a half-baked approach.  The restrictors were removed from the air box as per Power-Up guidelines, and the OE manifold was round like your non-California engine.  (My bike sold originally in Texas.)  The needle-and-seat, the pilot jet and the muffler tip were Power-Up variety, too.  For the longest while, I could not imagine why the engine had every Power-Up Kit mod except the 175 main jet.  It finally dawned on me that the previous owner may have reinstalled the 125 jet when compression dropped and the engine seemed to run rich.  This was from the intake valve damage and loss of compression, not from over-fueling the engine with a 175 main jet at Texas.

 

Those familiar with my books and journalism know that I do not make assertions that fly in the face of OEM norms.  My jetting recommendations are Honda's own, both stone stock applications sold outside the U.S. and the "kit" that was allowable for these bikes as "off-highway" use only.  Off-highway or "competition" improvements do not violate EPA and California emissions because the bike is not presumed to be street ridden.  (There is a Green and Red sticker program in California, but we'll leave that issue alone.) 

 

Note: There's a jetting chart and comments at http://xr650r.us/jetting/.  What you'll discover is that the baseline for the author's chart is a 175 main jet at sea level.  He adjusts for both altitude and ambient temperature.  His main jet chart goes as high as 182 (sea level at 20 degrees F) and as low as 150 (for 12,000 feet elevation and 100-degrees F if you can find such a place on Earth!).  Nowhere does he mention a 148 or smaller main jet.  He talks about the HRC and Power-Up parts and also the Stage 1 camshaft that I'm running.  His chart includes needle settings for the B53E needle and seat package. There is also commentary about the standard pilot jets versus the "S" pilot jets. The author and I believe that reading spark plug coloration is a sensible backup to any jetting experiments.

 

So, what you need to do is compare your bike to mine, and that's not difficult.  At the magazine's free articles and how-to videos on the XR650R work, and clearly at the highly detailed 54-minute HD video how-to I did on rebuilding the top-engine (a streaming rental at Vimeo), you can readily follow the camcorder and photos as I show the intake manifold, the tailpipe and the unrestricted air box.  These parts are easy to spot and compare.  Whether you have the N.A. type tailpipe tip or the Power-Up Kit version will be clear.  There's considerable size difference in the tailpipe outlet. For a quick comparison, see my coverage of the TCI rack installation.  The muffler and tailpipe tip are prominent in the article's photos and the video.

 

Worth noting, I stayed with the stock air filter box, air filter and flame trap.  I tossed out the popular brand aftermarket air filter that could not seal properly at the edges.  (You hint of a similar issue, Greg.)  I'm now running the OEM Honda replacement parts, including a new flame trap screen, new OEM air filter and a new air box "O-ring" that seals between the black air box and the white side cover's lip.  I'm sure many have stories of performance gains and unleashing latent horsepower from aftermarket air filters.  I have no desire to periodically replace intake valves and service the cylinder.  Nikasil is very tough but can be seriously damaged by fine dirt running constantly through the upper cylinder.  Considering our alkaline dust at Nevada, I opted for the stock air filtration system.  The engine's performance is excellent, with no signs of air flow restrictions, and I'm good with "stock"!.

 

We're both very fortunate not to have the California suction valve system and other one-off pieces for the Golden State models.  If you have the wherewithal, consider doing a cylinder leakdown test for piece of mind. If you do so and the engine still has the auto-decompression OEM camshaft, make sure you back off the rocker adjusters enough to be certain all four valves are seated with the piston at TDC on the compression stroke.  Many try to run a conventional "compression test" on these engines, only to find that compression is a fraction of "normal".  An exhaust valve unseating as you kick through with the auto-decompression type camshaft will do just what de-compression is designed to do: release compression to ease cranking!

 

As I noted in a thread above, the Hot Cams Stage 1 camshaft is a sheer joy.  You and I can readily start a thumper with just the hand compression release lever.  (I describe my current kick starting technique, which differs some from the B44, but not in principle.)  Many seem to like Honda's auto-decompression, I cannot figure why.  On top of that, the camshaft's weight with the decompression mechanism is an awful lot of upper valvetrain mass to spin at speed.

 

Talking about speed, these engines when operated properly, which is to say by taking advantage of the massive low- to mid-range torque (more of both with the Stage 1 camshaft!), do not require redline throttling.  We understand this from having pushrod Beezers.  I had three of them, each '69s by coincidence, the B44, an A65L and an A75R Rocket III.  I actually liked the Lightning 650 twin on the road, it was far less weighty and more nimble than the A75R, although the A75R triple cylinder engine was significantly smoother and did tolerate extended high rpm operation.  Gene Romero (Triumph Trident) and Dick Mann (A75R BSA) proved this.

 

That said, do we plan to reenact "Dust to Glory"? (Watch this streaming from Netflix or rent the DVD, you'll see what an HRC version of the XR650R does for Johnny Campbell, Andy Grider, Steve Hengeveld, Mouse McCoy, the Roberts family team and others.)  Our rpm ceiling and riding may not create fuel starvation even with a 145 main jet.  An old tuner's trick, you likely know, is to run slightly rich, short of fouling the plug or fuel-washing the cylinder(s).  This keeps the upper cylinder cooler.  On the Honda XR650R, liquid cooling likely compensates some for the ultra lean mixtures in N.A. carburetors or even the Moose Racing kit.  Synthetic oil goes a long way here, too, and so does Nikasil.  A friend at Portland shares that just switching to Amsoil on his XR650R made his leg on the exhaust side of the bike substantially cooler.  I'd like to test and confirm this.  As you crack the throttle, you can instantly feel exhaust heat when the XR650R makes horsepower and BTUs!

 

What it comes down to is actual air-fuel ratio.  I am academic, and if I thought the 172 main jet was risky, I would install an oxy-sensor bung at the appropriate position on the muffler and test with an A/F meter.  More traditional testing, like spark plug color after hard acceleration and a quick shut-off, would be equally revealing. 

 

I can tell with my engine that the 172 main jet will work well at our altitude and with the Stage 1 camshaft.  If I encounter trouble above 6,500 feet, I might consider a change.  Short runs over Ebbetts or Carson Pass would likely not create an issue, I've done this with stock sea level and slightly leaner jetting on many of my motorcycles.  And planning for such a trip, I might simply install a hotter spark plug for climbing over the high passes.  I'll update on this point.

 

I look forward to our discussions, Greg, and hearing more about your bikes.  Happy to address our 2000 model XR650R motorcycles or the twin-carb XR air-cooled models.  Even happy to reminisce about BSA motorcycles...Thanks for joining us here, looking forward to starting new topics and threads!

 

Moses

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Hi Moses, I subscribed once I read your posts in this thread. I'm sorry to read about your misfortune with your xr650r. I just bought an 2000 XR650r a couple of days ago, I have no prior experience with them. I'm an old rider, I too used to ride a BSA B50 and have a 1982 XR500r and a 1984 XR350R. I've been trying to figure out if my bike has been "uncorked" as they call it. The prior owner knew nothing about any mods. The exhaust is not restricted. I pulled the main jet and it is a 145RD. The prior owner was satisfied with the performance, none of his friends could keep up with him. The rear sprocket was changed to lower the gearing for trails, so it probably was not ridden at WOT too much. That is what I'm hoping. Before I started the bike when I got it home I found the air filter leaking dust, so I have not ridden it yet. The rubber boot was still in the airbox but the plastic is not. While the filter is being shipped I have delved into the uncorking of my bike or lack thereof. Until I read your post I could not find anything definite about the stock jetting. The Moose kit has raised my brow as to the 145RD jet in mine. I just pulled the carb and there is no restriction in the manifold. This bike was sold new in Seattle. When my jets arrive I'll disassemble the carb and see what else is in there. Thanks for your informative post. I hope other xr650r owners will post what they found in their bikes before they "uncorked" their BRP.

 

Greg

Hi Greg,

 

I'm interested to learn of your progress with carb jetting on your bike. What altitude are you at, and what sorts of temperatures prevail when you ride?

 

As far as the rubber boot you mention - assuming you're not referring to the rubber o-ring that seals the air box to the side panel - if it's present, from my understanding, the bike is not fully uncorked. If you remove it, the bike will lean out further (more air in comparison to fuel) and the main jet will need to be bumped up "number-wise." Did you get a Moose kit? What is in it? I got one (EU spec, from a website in France, though I'm not sure that's any different from Moose's US version), but I don't have it where I am now, so I don't recall the specifics.

 

The bike that has fallen into my hands (2002 EU model) has the same problem as Moses's did - cylinder, piston and intake valve problems. It had been run without an air filter and with questionable carb condition and cooling system for an unknown period of time. I'm doing basically the same thing Moses did to rebuild it but without the cam. He's put a great video together, so I feel as if I know what I'm doing :). Luckily I'm on a trip to the US and I'll be here until the end of the month. Should be enough time to get all the right parts.

 

Next on the list is tires...

 

Good luck!

David

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Hi David,

I very recently purchased my XR650R. I have not installed anything on the bike. I've been trying to figure out what has been done to my bike by the prior 2 owners. I have ordered the proper jets for the carb and they should arrive Wednesday at the local dealer. The 145rd main jet that is in my XR may have come from the Moose kit, I only know from Moses that it is not a stock main jet. The elevation where I live is under 500' and where I will predominately ride in Western Oregon is around 1000'. We also ride in Eastern Oregon where the elevation runs between 3-5k. Temps very greatly between morning and afternoon and probably won't be a concern. They also vary considerably between the seasons. I plan to jet rich enough to cover my near sea level riding and only change if I encounter problems. I have ridden my 1982 XR500R in all these areas with not much noticeable change except starting when hot can take an extra few kicks at higher elevations. The odd thing that has happened more than once with my XR500R, is at high elevations in Eastern Oregon on a cold start is that it starts when I first push the kick starter trying to find TDC. The 82' XR only has a kick starter activated compression release. The slow lazy push can start the bike and has startled me more than once. I ride trails with my sons and seldom reach WOT so good low to mid range power with crisp throttle response is what I want. Like you I don't plan a cam change because I want smooth power throughout the RPM range and hotter cams tend to produce power in more of a sudden rush at a certain RPM. I wanted to ask Moses about how the Stage 1 cam preforms, but I don't know if he is familiar with a bike that has not been modified to compare. If my XR650R at some point needs a rebuild like his did, I probably would try out the same upgrade.

Please tell us a little about Burundi and what the riding is like in your country.

 

Thanks,

Greg 

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Hi Moses, 

I'm going to attach a picture of my exhaust screen. I should have shown the end, but it is empty and looks like yours from the rear. Please let me know how it compares to yours or one from HRC if you know.

It's frustrating having a new bike with all this potential and be waiting on parts, even if I can only ride it around my back yard for now.

Do you remember the handlebars on your BSA 441. I took them off my old B50MX and put them on my 82 xr500r. I don't think anyone makes bars for dirt bikes like these anymore. I'm not sure how I like them on the Honda yet, but I do like a narrow bar for tight trails or cross country, making my own trails in Eastern Oregon. One thing it does is keep my boys off my bike... they hate them.

The Stage one kit you put in your bike, was it from Honda or Hot Cams?

The Carb in my XR650R is a PE 78ABOA with the B enclosed in a square and a mark of some kind after the last A that is not a number or letter.

This bike supposedly had only 3 rear tires since new, but I take that talk with a grain of salt. I think it could have been used much more, but I got it for a good price. The down side is the seat height, I'm 5'8" and shrinking. I have read about lowering that seat height but in doing so it changes the geometry to the detriment of the bike so I don't plan on doing anything except possibly finding a softer seat. 

 

I bought my BSA new in 1974 and rode it into the 80's. My buddies all bought TT500's, after I got the BSA, but the BSA  lead the way most of the time with the guys I rode with. The TT500 came out right after I bought the BSA and I would have gotten one too, if I didn't already have the BSA. Other than that right side shifter, I loved that bike, limited suspension and all. Once I started riding again a couple years ago when I got the xr500r I couldn't believe how smooth the old 82XR was by comparison. Now when I get on the XR650 I think I'll find an additional improvement. I watched Dust to Glory last night for the 1st time. That is a great movie!

 

I bought my 1982 XR500, 1984 XR350 and a 1982 XR250r surplus from the State of Oregon as a lot.(My oldest son rides an 1986 XR200R we got separately). I never did know where they came from but I think they were all from the same place. The front ends of the 82's were bleached out from the sun and the seat from the 250 was sun rotted. The 250 was in the worst shape with missing teeth on the sprocket and a solid chain. I think it spent a lot of time on it's side. All three had their gas turned to tar. I don't know how long that takes, but I think it is a very long time. All bikes(I Believe) had their original tires but the 250's were sun rotted off the rims. All three bikes started after a carb cleaning and of course their tanks cleaned and new lines. I love Honda reliability.

 

Thanks, Greg

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Thanks for the insights, Greg! Our favorite places compass still bears strongly NW. I'm a U of O grad (W '80), and we lived a total of nine years at Eugene/Springfield and Oakridge, two stints, 1977-82 and 1990-94. I contributed the 'Drive Time' column to the Oregonian from 1993-97. Know both sides of the Cascade Range, can remember Bend when the population was only 10,000! Did Search and Rescue with the 4x4 club out of Oakridge, we dispatched to the coastal range and rivers, Willamette Pass and Waldo Lake.

We'll compare notes on our riding interests and venues. I have two good Oregon friends who ride on- and off-highway, one with an XR650R dual-sport conversion, he's based at Portland and works at Warn. The other friend from Oakridge days is now at Brownsville/Halsey and riding a WR250 Yamaha to work at Cascade Pulp—he's settled down since his Honda CR period at Oakridge!

I recall the handlebars for the Victor 441, they did have a good feel. That bike was an absolute blast and proved the point: You're always riding the "best" bike ever, because you need to be in the game on whatever's beneath the seat of your pants! The BSA thumpers felt great for that era. In the desert and scrambles, we didn't know any better. Brit bikes were racing the Baja! In hindsight, the minimal front fork travel was horrible, I can still hear the forks bottoming! Vertical rear coil-shock suspension, by today's standards, was also terrible. I get a kick out of "On Any Sunday", watching the four-stroke bikes tail dance across the desert, the riders bobbing up and down with the rear suspension...First breakthrough was cantilever shocks, then the mono-shocks and our Honda Pro-Link—such a monumental gain, thrusting the bike forward instead of straight up and down!

The seat height is high on the XR650R. I'm a 32" inseam, and it's a stretch. I'm back at the gym now, consistently after the magazine had me parked in front of the computer for longer than I'd like to acknowledge...I, too, discovered some height shrinkage. Stood 5' 11" at my peak, a recent check has me barely 5' 10". According to most, some of this is age, though denial has me thinking that by pushing away from the computer, working out more and riding the dirt bikes, I can stretch back to 5' 11"—if not, at least I'll be healthier and happier! Will update on the effort!

As for the exhaust and uncorking your XR650R, the Power-Up Kit difference is in the tailpipe tip. If yours looks like mine, you're fine. Not sure whether David's Euro model comes with the Honda Power-Up tip, I'd like his feedback.

Regarding my Hot Cams Stage 1 camshaft (not a Honda HRC camshaft, which is more like the Stage 2 Hot Cams), I went with the Stage 1 for two reasons: 1) When researching, and my concerns are exactly like yours, I discovered that the grind is actually for low end to mid-range performance gains, not mid- to top-end gains, and 2) as I noted, the auto-decompressor on the OEM camshaft did not thrill me. The Stage 1 camshaft eliminates the auto-decompressor system. (In the magazine illustrations and videos, you can see the parts differences.)

In a nutshell, I am thrilled with my engine's performance, very stable idle and immediate, massive torque from throttle tip-in to redline. I don't over-rev this engine and shift well below redline by instinct, there's absolutely no need to wring out this engine, it enjoys being upshifted and laying down torque in the next gear up. (A sixth gear would be nice, I do like the stock 14/48 sprocket arrangement for my multiple use riding but find myself, amusingly, often reaching for a sixth gear, conditioning from the earlier XR experience.) If you're okay with using the OEM manual decompressor lever for starting the bike, I highly recommend this camshaft if you want a change. Is it a "must" over stock, and should you go to lengths and change out the camshaft? Probably not—unless you develop the same disdain I did for the auto-decompressor setup.

Your XRs from the State of Oregon sound intriguing, what a find! The account of how little they needed to get going again does draw attention to Honda reliability. I have the '84 XR500R under a tarp (dry climate here at northern Nevada, fortunately!) and earmarked for restoration. It's completely intact and quite solid. Our youngest son bought the bike over the phone from a San Diego County owner several years ago. (This is the son who just bought the 2003 Honda XR400R with 134 original, documented odometer miles!) He rode the '84 XR500R about 20 minutes with blue smoke coming out the tailpipe and parked it.

I took the XR500R off his hands for what he paid for the machine, well worth it. This front and rear disc brake model is easily restorable, and as a seasoned professional motorcycle wrench, I would expect to rebuild any used 1984 motorcycle's engine. (Similarly, our fellow forum member Forman rebuilt his Kawasaki KLR engine.) For those of us who ride the desert, these XRs are great machines. Objectively, a vintage XR200R, XR250R or XR350R makes a bit better tight and twisty bike for single track trailing. For a desert playa or sagebrush 'Hare-and-Hound', however, either is the XR350R or XR500R is in its element. So is the XR600R, XR650R or any of the Honda CRF models.

Where do you ride at Eastern Oregon, Greg? Do you get to the coast, too?  Let's open up a topic at our single-track travel forum:  http://forums.4wdmechanix.com/forum/35-places-you-have-been/!  Would be great to add some photos and get David's moto view of Burundi, too!

Moses

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Hi Moses,  My parts order from the Honda dealer came in Friday. I found a picture online of the stock exhaust tip. The tip in my bike is different and by description I think it is the HRC tip. The main jet in my XR650R was 145rd, the slow jet was 65s, the needle was the same as in the power up kit and in the 3rd slot. I put in a new stock air filter, fired it up, and it runs very strong. I only ran it around a parking lot when I bought the bike so I can't compare very well, except to say the power feels awesome now.

 

I would recommend to anyone that has purchased an XR650R to check what they have in their carb, no matter what they were told by the seller. If for nothing else than piece of mind.

 

The only problem I have now is the seat is too hard. Are you living with yours?   

 

Greg

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So, what did you decide for the main jet?  If all seems well, check the plug after a hot, hard pull (without going to the ER burn ward from mishandling a scorching spark plug!).  You'll find that opening the throttle is something enjoyable on this bike, just don't wheelie the bike through the neighborhood!  On that note, power does go to the ground with the correct seating position, and opening the throttle does not have to result in a wheel stand despite the many YouTube examples of wheelies on XR650Rs.  If the throttle transitions feel strong and smooth, and the spark plug looks okay for coloration, go for it...If any have questions about spark plug coloration, I'd be pleased to respond.  Just open up a new topic, and we'll discuss it!

 

As for the stock XR650R seat, yes, it is hard, especially after an XR350R or XR500R seat from the day!  This is the newer, spare seat design, a weight and mass saving gesture, in addition to keeping the seat height as low as possible on this already tall chassis.  As for replacements, a number of aftermarket sources offer seats (Acerbis for one) that boast improved riding position and cushioning.  We've discussed leg length and inseam, and this can quickly get compromised by thicker seat padding.  Touch-and-go here!

 

Moses

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I put in the uncorking set that seems to be recommended everywhere. 175 main, 68s slow and the 3E needle. The needle was in there already, but I put in the new one and the holder anyway. I'm not a wheelie kind of guy, when I unload my bike at a riding area, it is common to see someone else making dust, noise, and throwing rocks in the parking area. That is not me.

 

I've got to do something about the seat. If it had seat foam like our XR350R's, I would be happy. I could sink into the seat and  lose a little seat height at the same time. Because the seat had to be thin Honda made it hard, so heavy riders wouldn't bottom out. I weigh about 150#  and a 2x4 provides about the same cushion. The 1 size fits all isn't working for me. My inseam is 30 to 31,  and it came into play last night. I was riding around my place and getting dark so I stopped to get off the bike and put it away.  I reached out my foot but it went in a depression in the grass that I didn't see and over we went. I've never done anything like that before, but this is the tallest bike I've ever rode and for me to reach the ground I must lean it over. When it is on the ground it is a BRP and a heavy one at that. My old BSA was 300# but the weight was low. I didn't have to lift it as far. The XR650R is much more top heavy. I've heard of 3 ways to lower the seat. Soft foam so you sit into the seat. Cut down the seat(still hard) Drill some holes in the foam so the seat can collapse. I heard there is a rear linkage kit too that can lower the seat but I don't want that.  I need to do something.

 

Greg 

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Greg...Very pleased that you followed the "Honda Power Up Kit" formula for jetting and the needle.  The OE restrictors are likely out of the air box, too, right?...You'll be happy near home with this jetting, and I'm getting away with nearly the same jetting at rides to 6,500 feet: 172 main with straight 68 pilot and the needle at #3 clip position.  Will test even higher altitudes this fall, I'm headed to High Rock Canyon and surroundings.  Will be filming from the bike, I'll share the link after our ride.

 

Like you, I've ridden a very long time without feeling compelled to do many wheel stands.  I got my first two-wheel "Scooter License" at age 14 in Nevada, that was 51 years ago.  The limit was 35 mph and 6-1/2 horsepower, which I quickly ignored, building an outlaw Cushman with 8-plus horsepower and a peak speed around 60 mph.  The XR650R power to the ground is tremendous, however, you'll have no problem keeping the front wheel on the ground, especially when hard desert riding.  You're used to the XR500R, just imagine that bike on steroids!

 

I thought your seat issue might have remedy at Acerbis.  Their X-Seat offerings for Honda do not include the XR650R.  I found a listing for a seat cover, and this could be more to your liking, anyway.  The cover might allow some room for additional padding, and a creative upholstery shop can perform magic.  Give these folks a call or drop them an Email to confirm whether the cover allows enough room for added padding:

 

  http://www.2wheelpartssupply.com/cycle-works-seat-cover.html?utm_source=google&utm_medium=paid_search&utm_campaign=paid_search_google_pla&scid=scplp203623&gclid=CjwKEAjw68ufBRDt0Zmrn4W_8AwSJADcjp1cXJ1sOqOMW2aLJ0ecHaHzfJJBioL8d2VfaEuWVsBjahoCV8Tw_wcB

 

A place to begin, you need to be comfortable in the saddle!

 

Moses

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  • 3 weeks later...

Hi guys,

 

So I'm finally back in Burundi, and I managed to get all my parts here without TSA in New York messing about too much wondering what the heck a cylinder and piston were doing in my luggage.

 

I have opened up my carburetor and have found essentially that it's the same as a power-up with the exception of the pilot, which is a 65s. I decided to leave it in there, rather than replace with what came in the Moose kit (65 not s). I will contemplate ordering a 68s if I'm not happy with how things turn out. 

 

Aside from the 65 pilot, the Moose kit came with a 125 (yikes!) main jet, and a needle stamped D630. Their needle looks exactly the same as the B53e that's in my carb, but it's hard to tell. Since this is not a wear item, I left mine as-is. I was slightly disappointed not to find a new rubber seal for the carb top in the Moose kit. I guess my old one will have to do.

 

What I was happy about, is that there was a new fuel screw in the kit. Mine (as mentioned above) had been jammed in and the head mangled by some ham-fisted idiot (before this ham-fisted idiot got his hands on it :) ). As you suggested, Moses, small drill and an easy-out did the trick. Once out, I found that it had no washer or o-ring on it. I doubt that would have much impact, but at least now it's all set with a new screw, washer and o-ring.

 

As far as the main jet is concerned, I opted for a 170 in place of the existing 175. My reasoning after looking at the general web-wisdom is to compensate for the high-ish temps and 3,000 ft+ altitude where I'll be riding. I have a 172 to try if this seems too lean, but if it seems too rich, I'll have to order a 168 which I didn't buy when I had the chance....

 

Next task... Installing the new cylinder and piston!

 

By the way, there's a good how-to for the carb at http://www.xr650r.co.uk/service/carb/carb.shtml. It can probably be found elsewhere as well.

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Hi, David...The 65s at your altitude could work very well.  I find the 68 (non-"s") works well for me, and I would run it down to sea level if riding there.  My needle preference is 3rd clip position from top of needle, and the 172 main jet works well for me. 

 

Your OEM is a 175, which confirms that Euro non-U.S./N.A. models use a 175 stock.  (Australian models are much leaner, another story altogether.)  A 170 or 172 will likely work well at your elevation.  I will comfortably use the 172 from sea level to at least a 7,000-feet ceiling.  Again, my primary riding is at 4000-5500 feet, and I do have the Stage 1 camshaft. 

 

Talked to a Baja 1000 racer last night at the BFG tire launch in Mexico.  (Just got back from the new All-Terrain KO2 light truck/Jeep tire testing, more on that later!)  He's run his XR650R on a 175 main and shares that this "sea level" tune is tolerable to 9,000 feet.  Given my current sense for the Keihin carburetor, I would be more conservative and stick with short rides at 6,500-7,000 feet elevation for the 170-172 main jet size.  I'll play with this in the future and comment further.  175 is fat and probably just "tolerable", not in any way optimal, at high altitudes.  This range of jetting may well reflect the forgiving nature of an XR650R engine.  Let's compare findings when you get your bike running.

 

Given that these engines have been tortured by factory 112 and 125 main jetting, with 145 bantered around as a "performance" jet in the aftermarket, 170 is certainly a place to start at Burundi for an uncorked (Honda Power-Up spec) or European spec engine.  (A North America OEM corked XR650R engine, and especially a California "AC" type, would be a whole different tune.)  With the uncorked style exhaust tip, round intake grommet/manifold, plus an air box with restrictors removed, you should be thrilled with the 170 main and 65s pilot.  Again, this carburetor and engine are not hypersensitive like a two-stroke, and buying a 168 jet seems unnecessary.

 

The washer and O-ring on your new pilot needle is practical and functional.  This prevents an air leak past the pilot jet threads.  An air leak will destabilize the air mixture and cause irregular idle and poor starting.  You'll now get an accurate setting, as the O-ring and washer will seal snugly.  Good!

 

I see that the main jet choice in the U.K. rebuild of the carburetor is a 172.  He's happy, I'm happy, you'll be happy with the 170.  On that note, you do have the same tailpipe tip as mine, right?  The same rubber intake manifold shown in the U.K. carburetor illustrations?  No air box restrictors, right?

 

In my experience so far, a 170-175 should work well for extensive riding at sea level.  You will not burn a hole in your new piston with a 170 at sea level, and some find that even a 165 will work okay in an uncorked engine.  Again, the main jet size addresses open throttle fuel flow volume.  Realistically, anything from 155-175 will likely produce a lot of horsepower at higher rpm.  I find, however, that 172 seems right for great roll-on throttle at any rpm with very smooth power flow.  It just feels right, and you'll have to ride your cycle to know whether the 170 is your optimal formula or not.  The 65s pilot jet should work just fine at your altitude.

 

Looking forward to the best outcome from your top end rebuild...Let us know how that's unfolding.  When you are ready to run the engine and test ride, the success of your carburetor tuning will be very clear. 

 

I may do a short video on how to start a Honda XR650R.  Way too much discussion online with exotic starting procedures.  I believe many riders are flooding their engines to death.  Not necessary!

 

Moses

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Hi Moses,

 

I have the same exhaust as you and Greg, but mine has a frying pan rattling around inside. Must have been an option for those who really want to rattle the windows. I will cut the muffler apart downstream of the collector and see what I find in there. I'm 99% sure that it's the tack welds of an internal pipe that have failed. The easy part is opening it up. Then I'll need to find someone who can weld (or braze?) it back together again.

 

And indeed, my bike has no restrictors or snorkel in the airbox (nor in the carb insulator).

 

D.

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David...I like your can rattle metaphor!  Had a special moment at Baja, Mexico this week.  We were inland 60 miles from Ensenada, middle of nowhere, storm clouds brewing, stopped for a driver change in our Ford Raptor pickups and racing buggies.  The setting would be homelike for Burundi, I'm sure, the humidity spiked up, thick clouds threatening rain, puddles dotting the dirt road, obviously from overnight cloudbursts.  Suddenly, I hear a familiar note, the staccato of Honda XR motorcycles.  Swarming into a group, just up the road, were a bunch of hardcore dirt motorcyclists.  They were tackling our route and obviously hitting the higher gears.

 

While we chatted about race vehicles and the new BFG All-Terrain KO2 tires, I watched 10 bikes launch down the road at 150 yard gaps, just enough to quell the dust.  Yep, the distinctive exhaust notes were nearly all Honda XR650Rs, there was a lone XR400R also clipping through the gears!  The exhaust notes rapped out, and you knew they were having a good time! 

 

Two engines will catch my ear: the Honda XR650R and a P51 Mustang's supercharged Rolls-Royce Merlin.  We now live near Reno and were at Yerington, Nevada for the 15 previous years.  The Reno Air Races (this weekend at the old Stead Air Base) feature P51s, and the pilots often test in the skies over our area.  I've been to the races and spent as much time in the pit area as the grandstands.  These modified V-12 engines are formidable, and the huge props have a distinct pitch in flight.  An approaching XR650R or P51 will spin me on my heels.  In still air, you can hear a P51 from miles away.

 

I have some welding how-to videos at the magazine site if you have the equipment.  The steel in the muffler should be easy to gas weld if you do not have a MIG or stick welder.  You'll have more control and uniform cool down with oxy-acetylene welding.  (Better not to braze here.)  If the inner parts are the same material as the outer canister, I'd use ER70-S2 filler rod, commonly available.  (A "coat hanger" weld would likely work at remote Baja!)  Make sure there are no gasoline fumes in the muffler before welding!

 

Type the word "oxy-acetylene" (without quotes) into the magazine's search box at www.4WDmechanix.com.  You'll return a list of links for my gas welding instructional.  Enjoy!

 

Moses

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Having now figured out how to post a photo (thanks Moses), here are the innards of my pipe. It sounded like a frying pan, but it was really the kitchen sink!  

 

 post-290-0-51713800-1410781333_thumb.jpg

 

I've yet to check out the welding resources on the magazine site, but I will. Even though I won't be welding it back together myself, it'll give me a sense of knowledge for when i find someone who has the equipment and skills.

 

D.

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The gas welding (oxygen-acetylene) process is optimal for this fix, David.  The amount of oxidation rules out TIG, it would be near impossible to descale the parts sufficiently for that process.  MIG (GMAW) is an option, a talented stick (SMAW) weldor might be able to do the repair, too.  (Maybe a pipeline trained Burundi welding expert?)  Thinner gauge, older metal like this, I really like oxy-acetylene.  Check out the magazine video examples, you'll understand my enthusiasm for gas welding in these cases.

 

When you have the piece repaired, make certain the weldor positions the two shell parts as they were originally.  Given the bends and twists in the muffler assembly, off-setting even slightly would have dire consequences when trying to reinstall the muffler! 

 

Should turn out well, this is resourceful and saves considerable cost.  There are several aftermarket mufflers for performance gains (FMF and others).  You've likely racked up enough startup costs for now!

 

Moses

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Moses, you will note that indeed, a gas welding solution was found. It might not have been done in the "clean room" environment you would prefer, but I guess it'll have to do the trick. 

 

What I did was to go around the "technical" neighborhood asking welders if they could show me samples of their work. Having established that this guy actually had the necessary tools (rudimentary as they were), I settled on what would be considered locally as an exorbitant price (about $20) and he set to work re-assembling my muffler.

 

The end result is not super beautiful and I'm tempted to take a grinder to some of the rough spots, but it's good enough. The worst of it is hidden by the side cover. In the end, a grinder might be counter-productive as the weld material looks extremely porous and any diminishing of the material volume might lead to leaks. I painted it with barbecue paint (800 F test - best I could get), and tomorrow it will be put to the test. Not sure if it's gonna hold up under the temps generated by this bike, but we'll see. Maybe I can try to "bake" it on in stages during the break-in.

 

Back to the tools and materials side of things - you will note the "milk can" in the photos. This is the acetylene supply. What they do is to toss a lump of "carbonite" (which is essentially charcoal from Eastern Congo) into this vat. The only other thing in the vat is water. However, it somehow magically produces the acetylene. They took it seriously enough to set this vat away from any open flames!

 

Fun!

 

D.

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post-290-0-25792900-1410989732_thumb.jpg

post-290-0-38829500-1410989768_thumb.jpg

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Fascinating, David, the photos say it all!  I haven't seen innovative welding like this since watching the BMW frame repair at Mongolia during the 'Long Way Round' movie with Ewan McGregor and Charley Boorman.  Hey, ya gotta do what ya gotta do!  (A great song, incidentally, recently resurrected in the movie "Blood Ties".  I knew the Johnny Rivers version from my high school days, the soundtrack in the movie was Al Wilson's take.)

 

The key to success with welding is the complete fusion of metal that underlies any weld.  What you want here is enough heat to melt the base metal on each side of the weld, then the insertion of a metallurgically appropriate filler metal into the molten puddle. 

 

This technology may not warrant discussion with these weldors at Burundi.  However, I never underestimate the capacity or skill of any practiced weldor.  Fortunately, welding is as much a hand/eye and intuitive application as it is academic and technical.  When I taught welding, we had a particular student who did well with oxy-acetylene and went directly to TIG, laying down exceptional GTAW welds.  Upon graduation, he wound up performing aircraft engine impeller repairs.  His training was no different than others, and some students, frankly, failed to master the craft, never grasping how much heat to apply or when to dip the filler metal into a liquid puddle.

 

When I watch weldors, I'm absorbed in their "process" and immediately conscious of right moves and wrong.  This is from practice that began with a year of welding training in high school.  I was fortunate enough to experience the post-WWII methodology:  start with basics and get as much hands-on time as possible.  Our instructor, who doubled as the FFA (Future Farmers of America) chapter advisor, repeatedly drove home the fundamentals.  As a result, we each learned to gas weld, braze and stick weld properly.  I thank Mr. Gray, he paved the way for my later training and many years of professional welding around engineering plant repairs, heavy equipment repair work and automotive technology.  When I can muster the time, I'd like to produce a series of welding instructional HD videos and impart that experience.

 

Best not to grind off any metal...I'll keep my eye open for a pristine stock muffler, David.  Often, owners discard the OEM system when upgrading to performance equipment...Maybe we can drum up a backup unit.

 

Moses

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Hi Moses,

 

I guess indeed, I gotta do what I gotta do. I went to check out both versions. Even though I grew up (at least part of the time) with AM radio, the Johnny Rivers version didn't ring a bell. The Al Wilson cover however made me think of Tom Jones. I hope I'm not cheapening your memories!  B)

 

Not to change the subject; but the sound of my locally rewelded stock pipe with "Euro" tip, is a sweet and crisp song. Unfortunately it hasn't lasted. More detail on the engine rebuild thread.

 

D.

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David...So, we get Netflix and watched "Blood Ties".  The soundtrack was right out of my high school era, I graduated in 1967.  Johnny Rivers was popular, we lived at a rural ranching community.  A handful of my school chums were into British rock.  Johnny Rivers, Roy Orbison and other country/rock singers worked better in the local Nevada cowboy bars...I got into everything Motown shortly after high school but always enjoyed Johnny Rivers.

 

When we watched to movie, I was jerked back in time and went on a short refresher tour at YouTube around "Do What You Gotta Do".  After Johnny Rivers, there was Al Wilson, Tom Jones and down the list.  This was one of Jimmy Webb's greatest hits, he fueled the successes of Glenn Campbell and many others, including Johnny Rivers, obviously.

 

Here's what I found if anyone is curious:

 

"Do What You Gotta Do"

Classic Jim Webb sung by Johnny Rivers…

 

https://www.youtube.com/watch?v=7NSjT27M3M0

 

Here’s a year later (1968) and Al Wilson pressing the same song on a 45-rpm disk at the UK.  Note that Johnny Rivers is shown as the “Produced by” on the label…This is the true “soul” spin, a very clear and clean vocal rendition:

 

 https://www.youtube.com/watch?v=j7WzqirnQRI

 

I actually like this Al Wilson cut better, there’s also a “Comment” below by someone who heard this song in “Blood Ties” and got a rekindle like I did:

 

https://www.youtube.com/watch?v=hi02YH039tg

 

Tom Jones couldn’t leave it alone and does a very decent rendition, especially as a live performer, getting "Tom Jones theatrical" at the very end.  You can see how much traction the song had at the time, this is still the late ‘60s:

 

https://www.youtube.com/watch?v=hMCjdnC40nI

 

This version goes far afield by Roberta Flack, a soulful rendition that relies totally on the lyrics, a major departure from the original rhythm and melody:

 

https://www.youtube.com/watch?v=UFIZXCoOIm0

 

Also from Roberta Flack, who had a vocal gift, this significant breakout song became best noted for its role in the soundtrack for “Play Misty for Me”, a movie starring Clint Eastwood that was a sensation in 1971:

 

https://www.youtube.com/watch?v=Id_UYLPSn6U

 

Nina Simone does it, too:

 

https://www.youtube.com/watch?v=2jQC6L5Z108&list=PL79EA484ED19DD8CD

 

This is the Four Tops version, which is very well done, too.  Motown overtones for sure.  Lead singer Levi Stubbs nails it, he's Jackie Wilson's cousin, each had a great voice:

 

https://www.youtube.com/watch?v=U0svbAv8bDQ

 

If this resonates, enjoy the flashback.  That era spurred my purchase of the three BSA motorcycles in the early '70s.  Unlike Bob Dylan's short interest in a Triumph (long enough to make an album cover at least), I never fell off my Beezers!

 

Moses

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  • 2 months later...

Hello, please tell me the best jetting for my XR650R. I just install a Big Gun exhaust system and jet it acordingly, but It is hard to start and when it finally start, it was hard to keep it running.

I opened the pillot screw up to 4 turns and then it idles better, but has a sluggish response off idle. I opened it 2 more turns and tried to run the bike, but still has a sluggish response off idle that almost turn it off. I run about 1/4 mile, get back home and felt the engine hot and turn it off. I don't know if the carb has 2 mixtures screws, since there is a cap below the fuel intake hose, and others Keihin carbs has 2 mixture screws.

Mods before the BigGun complete system:

1. 175 Main Jet

2. B53E Needle, clipped on the 3rd

3. Slow Pilot #68S

4. Uncorked, UNI Filter, and Side Panel opened for better air inflow

5. open Insulator or Manifold

6. BigGun slip-on muffler

It was running good, and then I installed the header. My new mods are:

1. Big Gun header and muffler, wrapped with a “Lava Rock/Titanium Wrap

2. 180 Main Jet

3. Slow Pilot #72

4. Engine Ice.

I live at sea lever, what should I do? I really appreciate your help.

Thank you.

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Arnaldo...Thanks for being detailed...The OE carburetor has only one idle mixture screw.  I am concerned about the need for a 180 main and 72 pilot due to just the addition of the Big Gun.  (175 would be rich at my altitude and typical running environment, 4200-6000 feet.)  I run a 172 main and 68 (non-S) pilot.  Even these jets flow fuel on the richer side, although I'm not running a tuned exhaust like the Big Gun.  I run an uncorked exhaust tip, basically Honda Power Up Kit.

 

Everyone leaps to tuning.  I'm very particular about making sure the basic engine condition and settings are correct.  I would want to know the cylinder seal (leakdown test with the valves all closed) and also the valve clearances.  A third and ever-present concern with the XR650R is the auto-decompressor mechanism on the camshaft.  As you know, I eliminated the auto-decompressor guesswork with the installation of a Hot Cams Stage 1 camshaft.

 

Begin by making sure your compression is adequate and normal during cranking.  I would return to the 175 and 68S jetting to restore the good starting condition once more.  If doing so allows normal starting and idle, do a traditional wide-open-throttle run and shutdown.  Then, without burning your fingers, remove the spark plug.  Read it.  Share photos, I'd be glad to comment on the burn/mixture shown on the spark plug.

 

As a footnote, if the float level became distorted while changing the jets, the engine could be either starving or flooding.  What does the spark plug look like now?

 

Pleased to assist, Arnaldo.  Let's get that XR650R running properly and reliably!  The Big Gun should make a positive difference.   I would like to know how much...

 

Moses

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Hi, just changed to a 190 main jet, the needle on the 4th clip, and accommodate the pillot screw at 1.75 turns out (between the two points in which the rpm changes). It is working better, but still a bit sluggish when try to accelerate abruptly from iddle. It stalls if I keep the throtle on.

I'll try changing the needle to the 5th clip.

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Thank you Moses. I made the comment above before seeing your answer.

I start my bike just the same way you do. First or second kick as usual. The bike was running great with a 175 main jet, 68S pillot, B53E needle on the 3rd clip, open maniflod, open side panel, and the BG slip-on, it was totally uncorked. But I wanted the header and then, everything change. The jetting job is harder than I thought, but really interesting.

About the tests you recomend, I don't have those tools for the leakdown test, but I adjusted the valves last week, keep the UNI FILTER cleaned, oiled, and correctly sealed, motor oil is new as allways. Haven't change my cam jet, so the auto-decompresor is still there, but I am wondering how the feel of MORE grunt on low and mid would feel with that Stage 1 you have. The float, I am very careful with it, and did measure the 16mm. The spark plug is new and will try that traditional wide-open-throttle run and shutdown to send those pictures. I haven't done that before, so I may use your expertise.

It have been raining all day here and is imposible to test the bike like this Let see if i have the chance tomorrow. I live in Puerto Rico, and use my bike everyday commuting to my job. Here we have a high humidity (over 65%, sometimes goes up to 85% without raining, and it use to rain a lot). Temperatures between 65˚F to 95˚F (with that humidity… it seems to be 105˚F). Altitude:

o Normally between 0 to 500 feet over sea level (Monday to Friday)

o Occasionally between 500 to 1,500 feet over sea level (on Sundays)

o Less frequently between 1,500 to 4,000 feet over sea level (twice a year)

Well, thats the big picture. Thank you for your help, I'll keep you posted with those changes and the result.

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Arnaldo, all of these details are very helpful.  I am certain that you will find the 190 main jet excessive, but that will be at mid- to full throttle.  The idle and tip-in throttle issues are likely related to the pilot jet size and the needle height. 

 

You're headed richer with each of the changes.  5th clip notch from the top of the needle is a high setting.  I believe this is way too much fuel flow.  If the engine is tolerating this kind of richness, there may be an air leak at the manifold or carburetor/intake grommet, which would lean out the mixture.  The 1.75 idle screw setting is very close to normal and a good sign.  Be very careful with this idle screw, its inner stem is small and easily bent if the screw is removed completely and installed with this fine tip even slightly out of center.  (This is fairly easy to do.)  A bent inner stem on this screw would make it impossible to set a stable idle.  From idle to as much as 1/4 throttle speed would be unstable.

 

Did you run the engine after setting the valves, before the exhaust and jet work?  Was it running well after that valve adjustment?  Or did you adjust the valves at the same time you installed the Big Gun exhaust?  If the valves were adjusted at the time you installed the exhaust, I would carefully check the valve setting again.  Be sure that the auto-decompressor is completely off, and the piston must be at TDC (top-dead-center) on the compression stroke.  Maybe the valves are set too loose or tight.  If there was a considerable adjustment at the exhaust valve side, the auto-decompressor may have been interfering with your clearance check.  A possibility.

 

If the plug reading is rich once you get the idle stable and such, I would restore the jetting to your original settings of 175 and 68S as a baseline for sea level.  The engine should run okay with these jets, and if it is running very poorly with the 175 and 68S, with the needle in the original 3rd position, I would check for other possibilities and not change the jets yet.  When you do have the engine running well with the 175 and 68S, if the plug shows a lean mix, you can try the 180 and 72 that Big Gun recommended. 

 

The downside of running too rich is that the excess fuel will wash lubricant from the cylinder wall and cause premature piston ring and cylinder wall wear.  Too lean, of course, is not good, either.  Lean mixtures can overheat the engine, cause detonation, and damage the rings, piston and valves of the engine.

 

The spark plug color tests may require some thoroughly clean backup spark plugs for accurate readings.  Spark plug coloration is a valid and useful way to confirm the air/fuel mixtures at various throttle settings.  Again, idle to 1/4 throttle is mostly the idle screw and pilot jet, with some needle jet involvement.  Rolling past 1/4 throttle involves the needle height setting and gradually becomes a main jet size concern as the throttle gets wider and the slide with needle rises.  From a 175 to a 190 main jet on the XR650R Keihin OE carburetor would not make a lot of difference until the throttle is rolled open.  Unless there is something really exceptional going on with the Big Gun slip-on exhaust, the needle height should be 3rd or 4th clip groove at the most. 

 

Note: My engine transitions smoothly from idle to full throttle with the settings I've outlined.  The transitions indicate proper jetting and needle setting, tested by gradually increasing throttle and noting the engine smoothness at each throttle setting...For my engine, there is not the slightest hesitation, surge, balking or stalling at any throttle setting.  If I set the idle speed at 1400+ rpm when the engine is barely warmed, idle speed will creep up slightly after a hard run.  I prefer this to turning the idle speed screw up and down constantly like many describe.

 

Since your engine seemed to respond better with the very rich 190 jet, make sure you have adequate fuel flow from the tank to the carburetor.  The filter in the tank (above the petcock) may be clogged or damaged. 

 

Moses

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Hi Moses, thank you for all that information. You are very helpful.

Mods to date:

1. Main Jet 190

2. B53E Needle, clipped on the 4th

3. Slow Pilot #72

4. Uncorked, UNI Filter, and Side Panel opened for better air inflow

5. open Insulator or Manifold

6. Big Gun header and muffler, wrapped with a “Lava Rock/Titanium Wrap

I tried it today. It was hard to start from cold, but I insisted and it start, and I managed to keep it running. Still a bit sluggish when I tried to accelerate abruptly from idle, and it stalls if I keep the throttle on.

I took it to the street. I believe it was as you said, there was too much fuel with the 190 main jet and as a result, it was sputtering at top speed. But it really gets there fast, the header makes it loose.

I stopped at a gas station, press the kill switch and it made a "pluff" back fire, as if there was too much gas in the chamber. It started on one kick. When I get home, I let it idle for a minute or so, and turn it off. Tried to start it again, but it was flooded. Enough for today.

I will change back to the 180 main jet again, keeping the needle at the 4th position.

About your comments:

Only one valve was adjusted, the left intake was 1mm loose. It was at the same time of the header installation, but I double check everything when adjusting those valves.

When does the auto-decompressor is completely off? I use your strategy to start my bike, using the manual decompressor.

When I first installed the header, I tried it with the 175 and 68S, with the needle in the original 3rd position. The back fire was a great flame when I cut the throttle, and then I stopped the motor and decide to wait for the jet kit I ordered.

I didn't tried the transitions from idle to full throttle.

Thank you Moses.

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Arnaldo...Very pleased to hear about your detailed work.  The auto-decompressor has a one-way clutch mechanism.  You need to rotate the crankshaft very slowly in its normal direction of rotation and do not pass the TDC mark on the compression stroke.  If you do pass this mark, continue rotating, nearly 2 full crankshaft turns, until the TDC mark just lines up on the compression stroke.  Do not try to rotate the crankshaft backward to get TDC.  With the spark plug removed and the rear wheel raised slightly off the ground, you can put the transmission in a higher gear (4th or 5th) and control the rotation of the crankshaft by slowly rotating the rear wheel.

 

The valve adjuster screws should have similar height, not the same but not extremely different heights.  If you need to back off the adjuster a lot on the exhaust valve with the auto-decompressor (at the right side of the engine) to get any valve clearance, the auto-decompressor is likely engaged.  Rotate the crankshaft to TDC on the compression stroke once more and see if that clears up the auto-decompressor issue. 

 

Note: The left side exhaust valve opens from the manual decompressor lever at the handlebar.  Make sure there is normal free play at the cable to allow this valve to close without any interference from the manual decompressor.  This is the cable at the left or spark plug side of the XR650R cylinder head.

 

Your change to the 180 main jet will help.  When you can ride the cycle with dependability, the spark plug coloration and smoothness of the carburetor transitions will let you know whether the jetting and needle setting are correct.  Checking the spark plug after running the engine at various (sustained) throttle settings is helpful.  I'd be pleased to comment on the spark plug coloration.  Make notes about the engine's speed/throttle opening for each photo.

 

Moses

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Hi Moses, you really are there for us. Such a quick response, thank you.

I do exactly that to adjust the valves; on 5th gear. Also, I insert a straw through the plug hole just to see the movement.

The decompression lever has its normal free play.

I will do those tests this weekend and get back to you.

I remember there is another issue, I bought the XR with a different spark plug. Since it works really good, I kept buying the same. It is the NGK bcpr5es; it is hotter, but I don't know if there are bad consequences. Which spark plug should I use for those testings? Do you have a special plug for your cycle?

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I've just switched to the Enerpulse Pulstar spark plug after testing these plugs and researching their capability.  Here is the coverage and also an opportunity to see my Honda XR motorcycles in action:  http://www.4wdmechanix.com/Testing-the-Enerpulse-Pulstar-Spark-Plugs.html.  The video shares my riding venues and why I selected this spark plug.  The Pulstar spark plug helps offset short-term altitude changes without the need to alter jetting...

 

For your testing, since you're at sea level and we want a consistent baseline, I suggest the NGK BKR7E-11.  (The Denso K22PR-U11 is an alternative if the NGK is not readily available.)  The NGK BKR7E-11 is the factory standard listing for the Honda XR650R.  The BKR8E-11 is colder and optional.  Being colder, I would not use the "8E" while you're experimenting with fuel mixtures.  I would also avoid using a "performance" spark plug like the Pulstar until you are certain the jetting is correct.

 

I'm looking forward to seeing the results, Arnaldo!

 

Moses

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Hi Arnaldo.

 

You may have already found the solution to your problem, but I would suggest that you go back and very carefully check the valve clearances - especially the exhaust valves. I recently rebuilt my engine (bike was new to me) and I had a world of trouble to adjust the valves correctly. I went though all the different possibilities about ten times before realizing that the valves were simply NOT adjusted correctly. Before I got the clearances correct, the engine was exhibiting behavior similar to yours. I'm not a mechanic by trade, but I'm somewhat adept, so I'm surprised a valve adjustment should have been so difficult.

 

The culprit is the autodecompressor system that sometime seems to stay engaged no matter how much you turn the engine over. The best way to turn over the engine is from the crankshaft (remove the left side engine cover) with a long bar attached to a 14mm (I think - or maybe 17) socket. It will give you very good control so that crankshaft engine doesn't reverse rotate. One indicator that the autodecompressor is released is a loud "click" on each rotation.

 

Good luck with it! 

 

David

 

Escribí en Inglés porque soy perezoso - sino también en beneficio de otros que podrían no leer español!  ;)

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Gracias David:

Last weekend, I tried with a 185 jet, but not before I check the valve clearances (3rd time, just in case), float level, clear emulsion tubes, change the spark plug and check it really sparks... But this time it just didn't want to start, it was like a workout.

I opened the carb again and found some black particles that makes me think about dissolved o-rings, maybe from the petcock. I ordered the needles and brushes, so I will disarm and clean the carb. I have read that submerging it in boiling water with lemon juice will clean all its parts. I know there are carb cleaners, acid, and other methods, but want to know what have you done that works. Also, I may need to get a carb rebuit kit that have those emulsion tubes I have read on the forums. Please give me advise on this.

Thank you.

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Hi, Arnaldo...Not sure whether your local fuel contains ethanol.  If so, I can share two brief stories that may apply here...

 

1) Story #1: My Honda XR350R motorcycle has been in the "fleet" since the mid-1990s, it has dual Keihin carburetors that many consider problematic.  I have no problem with these primary/secondary carburetors whatsoever, they have worked flawlessly under every kind of operating and starting situation without the need to re-jet from 2500-7000 feet altitude...Base tuning/jetting is for approximately 4000-4500 feet elevation.  The bike has a SuperTrapp exhaust, tuned correctly, which I believe makes the engine far less altitude sensitive.  

 

5-1/2 years ago during a move, I parked the motorcycle and did not drain the fuel bowls.  The cycle stayed parked way longer than expected, more than two years...The pilot jet on the primary carburetor had been exposed to ethanol pump gas, and when I attempted to start the engine, it was very difficult.  The engine would not idle and only ran smoothly from approximately 1/4-throttle and upward.  This was the classic symptom of a clogged pilot jet.

I tried to spray clean the pilot jet, the fuel pickup tube and the idle screw passageway using NAPA spray carburetor cleaner, which usually works very well.  Not this time, the engine would not idle.  I removed the pilot jet and discovered that the fuel orifice was clogged so badly that a dip in Berryman Chemtool Carburetor and Parts Cleaner did nothing to clean up this pilot jet.  The cleaner thoroughly cleansed the carburetor body, fuel passageways and other carburetor parts by simply following the directions.

Note: The 50-State VOC compliant version of this cleaner in a 96 fl.oz. kit works very well for motorcycle carburetors.  (See details at the link.)...Dipping and rinsing with warm water is typically my cleaning process, wearing eye protection and nitrile or protective gloves around any carburetor cleaner.  Keihin carburetor bodies look like new when dipped and rinsed, and blowing out the passageways with compressed air further restores the carburetor.  Every part of this cleaning approach turned out well except the pilot jet, which remained clogged.

Clearing a clogged brass jet is very unpredictable.  Use of a tiny, properly sized "jeweler's" drill bit, a sized wire or a welder's tip cleaner is not sensible.  If the clogged jet is like "cement", there is a high likelihood that a sized drill, even turned with your finger tips, will move off-center and scarf out the brass wall of the jet.  Welding tip cleaners are obviously risky, as they are mini-files.  Unless you can clean the jet with carburetor dip or a similar chemical approach, consider replacing it...Lemon and water is a new one, I'm doubtful that it would unclog a solidly plugged jet.  I've used citrus and water-soluble alcohol cleaners with little success.  In fact, ethanol or alcohol water based cleaner is not much different than alcohol/ethanol fuel.  I might use citrus solution or an alcohol-based cleaner for "pre-cleaning" the carburetor before thoroughly drying it off then dipping in a bona fide carburetor cleaner like Berryman Chem-Dip.

So, the fix wasn't complicated:  I replaced the primary carburetor's pilot jet with a $6 Keihin replacement jet and purchased two overhaul gasket sets.  Shop around on this one, as Keihin is simply Keihin (short versus long jet style, match with the OEM jet).  There are many sources for these jets.  Honda OEM replacement jets are spendy.  I found this jet through a Kawasaki dealer.  Most independent motorcycle shops have direct lines to Keihin jet sources, too.

2) Story #2: The Honda XR650R motorcycle engine would not start...I bought the cycle in this condition from the previous owner.  First-off, the OEM petcock filter (plastic) had disintegrated from setting with fuel in the gas tank for some time—again, ethanol/gasoline.  I spent considerable time trying to kick start the engine before performing a cylinder leakdown test.

I strongly advocate meeting four criteria before trying to "tune" an engine:  normal compression, proper valve timing, proper valve lift (includes valve clearances or an unseated exhaust valve from the auto-decompressor like DavidEasum emphasizes) plus normal oil pressure once the engine runs.  These are not spark/ignition or carburetor issues.  Once these four criteria are okay, you can look for vacuum leaks, carburetor issues and ignition/spark troubles.

The engine failed the leakdown test and turned up with damaged intake valves from dirt seeping around the edge of the aftermarket air filter (a previous owner install).  I rebuilt the top engine, presenting magazine viewers with the process from the L.A. Sleeve sublet machine work to the actual teardown how-to overview.   My complete upper engine rebuild became available to owners as a Vimeo On Demand HD video rental.  Forum member DavidEasum was an early viewer/renter of the HD video.  David's rebuild has been a great success, which pleases me!

My XR650R's overall engine condition was now "as new" with the additional installation of the Stage 1 Hot Cams camshaft (no more auto-decompressor!) during the upper engine rebuild.  I then concentrated on air filtration, intake seal and the carburetor.  (The ignition was stock and tested fine.)

The carburetor findings were interesting:  Jetting was a 125 main jet, the stock North American recipe for meeting EPA standards and toasting the upper engine!  The pilot was a 68 (not 68s).  This engine was half-tuned with the uncorked intake manifold (stock 49-State type), an unrestricted air box and the Power-Up Kit exhaust tip!

The motorcycle had, in Western American horse language, been "ridden hard and put away wet".  Not abused, just thoroughly used!  My guess is that the 125 main jet had been reinstalled and not been in place for long.  Likely the previous owner could not get the engine to run "lean enough" due to the compression loss from the intake valve leakage.  He may have stuck the OEM 125 main jet in the carburetor to compensate.

Note: If the 125 main jet had been in the carburetor for a long time, this is a testimonial to two things:  1) the range of jetting flexibility for an XR650R engine and 2) the ruggedness of this engine in tolerating such an ultra lean fuel mix after being uncorked!  I'm guessing that a 125 main jet was not in the uncorked version of this engine for very long.  A 175 main jet would have been "normal" for the uncorking or "Honda Power-Up Kit" that was in place everywhere else.

I did a 172 main jet, providing enough fuel for the uncorked engine and a Hot Cams Stage 1 camshaft.  We're at 4,200 to 4,400 feet elevation, depending upon which end of the valley we stand.  I'm now convinced that a 165 or so main jet would likely work optimally for this altitude.  I do not have exhaust mods beyond the Power-Up Tip with a larger opening.  The muffler canister is stock.

Note: Currently, I am testing an Enerpulse Pulstar spark plug to offset the slightly rich-side 172 main jet burn.  The engine runs very well and did so before the spark plug change.  At this elevation, the 172 main jet produces a bit darker coloration than ideal but does not show over-rich fuel wetting.  This means I'm not placing the engine at risk of cylinder fuel wash, plug fouling or carbon buildup...I will watch the burn over time, my aim is jetting that will be tolerable between "low desert" (2,500 feet or so) to 6,500 feet for at least short periods of riding.  Primary jetting is for 4,000-4,500 feet.  The engine break-in is still underway (though you can't tell with this XR650R power-to-weight ratio!).  I'll leave jetting as is for now.

The "story" does not end here.  After rebuilding the top engine and performing the jet change, I finally did what should have taken place in the first place: removal of the carburetor, cleaning it and rebuilding it with a "kit".  (These carburetor overhaul "kits" are ridiculously expensive for the minimal parts included.  I went with OEM Honda here and would recommend shopping for less costly Keihin sources or aftermarket.)  The ultimate discovery was that the previous owner, in a hasty effort to get the motorcycle running (likely while I was en route to look at it!) accidentally left the slide linkage disconnected.

Despite the throttle return pressure, the carburetor slide was parked at the bottom of its bore.  This provided a sure way to get a considerable cardio-vascular workout with a guarantee that the engine will not start.  Use care when hooking up this internal carburetor linkage.  Make sure it will be intact and working properly 100 miles from nowhere!

When I finally knew this engine would start, I was still wary.  Other forums are rife with folklore on how difficult these engines are to start.  Intuitively, I know that every properly tuned motorcycle I've ever owned has started immediately, and I could not believe that Honda built a motorcycle that would not start readily.  (Imagine trying to sell a brand new Honda XR650R motorcycle at the dealership and having to go through a five minute ritual with guesswork about whether the engine would start!  Does that make sense?)  Fortunately, my theory held.  The engine fired on the second kick.

Soon I got even better at the starting sequence.  In my experience, which reflects the altitude and slightly rich-side jetting, the engine requires very little choke effort, especially in warm weather.  In fact, it's intolerant of over-rich starting.  With a piston approaching 350 cubic inch (5.7L) Chevrolet V-8 size, this thumper can flood quickly.  Unlike many owners who want to "load up" the engine with fuel, I'm conservative in both my choking and priming chores.

I'm sharing all of this to provide a broader view of how and when an XR650R engine will start.  Once you're very sure the engine should start, trust that it will and don't over-fuel it.  When very cold (ambient temperature), I will:

 1) Set to full choke

 2) Kick the engine through twice with the manual decompression lever pulled in and ignition off

 3) Find TDC under compression (decompressor lever released)

 4) Kick past TDC just the slightest amount with the decompressor lever pulled in

 5) Again release the decompression lever

 6) Turn on the ignition switch

 7) Kick through firmly with the throttle closed

😎 The classic adage: If the engine does not start after a few kicks, repeat steps.

When the engine fires, typically on the first run through these steps, I immediately take the choke lever down to half or even off, depending upon the air temperature.  If necessary, I will "feather" the throttle and not let the engine stall during the first mile of riding.  For me, even half choke is only for a brief time.

The idle may be unstable with the engine cold and choke off.  With the thermostat doing its job, the engine should be warmed within a mile or so.   Experiment here, as much depends on your riding habits, the altitude and temperature, and how much you care to coax a cold engine to warm up.  Less choke means less carbon issues, less risk of spark plug fouling and less risk of fuel washing the lube off the cylinder wall.  The Honda XR650R is carbureted and still kick start era, but it does not need to be a hardship to start or warm up.  If you want to get past these quirks, you need a contemporary CRF450R (how about a factory dual sport 500 version soon, Honda?) or a KTM plate-able dual sport 500 EXC with electric start and EFI.

Your idle mix screw setting is correct for initial start, Arnaldo.  Try to reset it only after running the engine to fully warmed up (unless it simply won't idle well at the current setting).  Idle speed of 1400+/- 100 rpm is factory and realistic.  This may seem fast to some, but the thumper fluctuates idle speed between cold and fully warmed.

Check things over.  Make sure the fuel petcock is not disintegrating within the tank and clogging the petcock and carburetor.  Let's get that XR650R performing at peak.  The Big Gun exhaust modification cannot impact tuning that dramatically, and I believe the 175-185 main jetting will prove plenty at sea level.

Keep in mind that the main jet flow has little to do with lower throttle settings.  Performance exhaust manufacturers have benchmarks like Johnny Campbell and Andy Grider battling it out in Baja, Mexico during the filming of "Dust to Glory".  Main jet recommendations account for wide open throttle desert racing demands.

Moses

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Hi Arnado,

 

Moses gives good advice above - as he always does. In PR I guess you have access to proper products like carb cleaner, I had to make do with gasoline and a borrowed air compressor. Whatever the case, water and lemon juice can't hurt (I may have to try it one day since I have a lemon tree in my garden that supplies us with more than we need for the kitchen!).

 

While the condition of the carburetor and jets will of course have an impact on how the bike runs, I would still be suspicious of the valve clearances (based on my experience). After my rebuild, the bike started right away and idled just fine, but the next day when I took it out for a shake-down run, it started to run poorly and refused to idle - almost as if it was running out of gas. I went through the carburetor about 4 times (even with a magnifying glass) trying to figure out what was wrong. It was extremely frustrating since every time I put it back together, it would run fine for a short while (once it was almost a day), and then stop.

 

Being that I didn't know what to do next, I checked the valves (although I really didn't suspect I could have done something wrong). The first time, I found one of the exhaust adjusters was very high in relation to the other one. (see photo) This was because of the autodecompressor.  I reset that valve, and the bike ran great again. But then it stopped. So I checked the clearances again. And once more, I found the valves were out of adjustment - this time it was the intakes. Somehow I must have been using a top dead center from an alternate universe. Once I corrected them, all was good and the bike has been running great ever since.

 

Now it's due for a clearance check and changing out the break-in oil. If I find anything out of the ordinary, I'll post.

 

A last thought is if you're going to open the carb again, follow this how-to from the web: http://www.xr650r.co.uk/service/carb/carb.shtml 

post-290-0-13114900-1417600016_thumb.jpg

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  • 7 months later...

Hello:

Finally, I am writing back after the fix. It is not that it took me so long, but I also did the wiring to DC and got all my lights LEDs.

I cleaned the fuel system so many times to get it unclogged. Bought a new petcock and a 4.6 gallons tank. Got fuel for up to 5 days of commuting. It's a good feeling to see the fuel station and not having to stop for fuel every other day.

Now the carb has: 180 main, 68S slow jet, needle on the 3rd with the shim. It start from the second kick when cold, and sometimes surprises me starting on the first. It is giving from 40 to 42 MPG, and that is a great contrast versus the 33 to 36 MPG when it has the 185 main, 70S slow, and needle on the 4th.

I found a fuel without alcohol that's working great.

I'm considering that Pulstar plug for my next step.

Thank you for all your help.

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You're very welcome, Arnaldo, please keep us informed.  If the bike is "uncorked", a 175 main jet at sea level might be even better than the 180, though these engines will tolerate slight enrichment.  I'm running a 172 main at 4400 feet and even higher elevation, slightly rich, enough to require coming off the choke immediately when the engine starts, at least to half-choke.  In summertime (now), I'm pulling the choke off completely after the engine starts.  Like your engine, mine starts on the first or second kick regardless of how long the bike has parked.  I'm very happy.

 

Really glad to see your fuel efficiency!  This is good mileage for a big displacement single cylinder thumper.  Might get slightly better with a 175 main jet.

 

Congratulations, enjoy the BRP, and ride for fun and safely!

 

Moses

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It was uncorked, and had the 175 main, 68S, and the B53E needle on the 3rd. Then I installed the Big Gun header, and it combines with the problems of alcohol damaging the petcock and carburator's o-rings. Thats why I changed the jets.

I use it mainly on the highway to commute to work, and that is why it is so efficient. What is the MPG of your XR650R?

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Gotcha, Arnaldo!  The header does make a difference in tuning.  Let us know how the header affects performance now that the jetting is spot on...Great work and attention to tuning.  Do you think the header is helpful in achieving such good fuel economy, too?

 

I've been very busy with work and constantly think about riding, the XR650R is a metaphor for cutting loose.  I am thrilled with this machine, it puts a smile on my face every time I do ride.  We're constantly reminded why these bikes won the Baja 1000 year after year, the roll-on throttle is unparalleled for dirt enduro bikes—to this day!  I've ridden sport bikes since the early 1970s, and frankly, the dirt underpinnings and lighter weight of this bike are more appealing.  Granted, I'm not excited about the idea of riding the XR650R on asphalt for 500 miles at a stretch  like I did with BMWs.  The stock seat is stiff as a board after 50-100 miles on pavement!  May do something about the seat...Another topic to start!

 

I'm posting some photos of a Triumph Tiger 800 with a Yuill Brothers (Freedom Cycle at Reno, Nevada) "Dakar look" upgrade and performance package.  Watch for it!

 

Moses

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The header makes this engine feel free. You should try it, specially because you already have the stage 1 cam. It is so loose, I'm sure that MPG have been increased because of the header. But remember, that 40 to 42 MPG isn't on a trail or the curvy roads of PR, it's on the highway (although it could be at higher speeds than recomended for fuel economy).

Please tell me when you fix the seat. I ride 18 miles to my job everyday, and know it could be demanding for a 100 mile trip.

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Arnaldo, I got a referral to this website/business.  They still offer a seat remedy for the XR650R.  I'll likely use this product.

 

Check out the video on how to install the cover, not very complicated:

 

http://www.seatconcepts.com/

 

The cover and padding installation makes sense.  Being closer to the source, I'd likely pay the $20 extra for them to install the cover.  This requires sending them my seat during the riding off-season.

 

Moses

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  • 1 year later...

Hey Moses,

It looks like it's been about a year since you visited this forum of yours -- I found the information discussed here super helpful.

I've wanted an XR650r since I was 14 years old. Dust to Glory is still my favorite.

I am walking in your exact xr650r steps. I just bought an Australian 2000 xr650r from an honest seller who I spend tons of time with talking about the bike. The bike I am most familiar with is my 2004 cr250r that has been built head to toe for the desert (I'm obsessed with Utah). I heard a lot of "rolling" noise in the top end of the bike (especially with my helmet on). Being unfamiliar with 4-strokes I bought the bike for a fair price. It's super clean; I just figured the rolling noise was inherent (the piston is like a Folgers can for God's sake). I promised to check the valve lashes before riding it.

Before I get into this, I must say that the bike ran GREAT when I rode it... a monster! Australian Model is a pure breed (aside from that lean main jet you were talking about).

I pulled the valve check covers off to check clearances. Hmmm, no clearance IN or EX... worried.

It had a K&N air filter on it.... I pulled the filter off in the light and I just about passed out. It was like a dirt wind tunnel. One thing led to the next I had the motor out of the bike.

  1. Cam = done
  2. Rockers = done
  3. Piston = done
  4. Cylinder = done horizontal scoring at the top of EX side
  5. Valves = done, packed in and trashed
  6. Cam chain and sprockets were worn for typical wear and tear..
  7. Pictures of everything in the link below

Needless to say, I'm re-building the head and top-end. For me the next step is prevention. Questions like, "is the oil system working properly?" and, "is the jetting on point?" started popping up.... this is how I found your site.

The air filter is the main culprit in my eyes for obvious reasons (the air boot looks like a dirt wind tunnel).

The bike is uncorked: 

  1. open muffler
  2. open manifold
  3. main = 175
  4. pilot = 65S which is weird
  5. needle = 53E on the second to the bottom position

I live in good 'ol Colorado. I ride here and as far south as Moab so 3000' to 9000'. I picked up a Stage 1 Hotcam, which will be its only modification besides being uncorked. 175 seems a little fat. My main concern is the motor's safety when I take it to the desert. What main size would you recommend? Should I find a 68S pilot and whats up with my clip position? Probably just the old rider tuning? 

If you will..can you give me some advice on the following?:

  1. What jets would you like me to run?
  2. float height options (I have no idea)?
  3. should I ditch that darn K&N? What's the most bomber air filter option?
  4. I've heard about a needle o-ring, what's the deal with that? Would you recommend it?
  5. What plug have you seen work best in this bike over the years?

Here are some off topic XR questions:

  1. I'm running really wide bars, is it okay that I run the throttle hand grip upside-down to afford me more slack?
  2. I'd like to run some strong lighting for night desert riding, what direction would you point me in lighting wise?
  3. I'm using the following service manual link. https://goo.gl/0FDef2 I believe it's universal. What do you think and if you think I need to order one, where would you recommend I get a Australian service manual?

If you ever want to plan a ride out in the desert, I'd be happy to coordinate.

Also, check this out for for an XR650r reference: http://teknikmotorsport.com.au/Honda-XR650R-Suspension-Mods remove choke butterfly and 165 main? huh

Photo's of everything here: https://we.tl/klDz7P3CGl

Thanks!

Costa

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20160513_185311.jpg

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Costa...Thanks for posting!  Your XR650R looks fantastic, bad to the bone!  When I took my Honda XR650R experiences into the magazine and forums, I looked forward to others joining the discussion.  Your reply is welcome and just in time for the Fall riding season, our last high country single- and two-track riding until the Spring thaw! 

The I-H Travelall in the background of your very cool photo of the XR650R is another thing we can share...A '66 Travelall with 304 V-8 and a small Scotsman trailer in tow was my first trip up the Alaska (Alcan) Highway in 1975.  I'm due for another...Ummm, on the XR650R?  Well, maybe not with the bear sleepovers.

See my comments below, and let's keep the dialogue going, Costa!  

Moses

On 10/1/2016 at 6:13 PM, Costa said:

I've wanted an XR650r since I was 14 years old. Dust to Glory is still my favorite.

Dust to Glory raised the XR650R to cult status...Purpose built for open desert enduro racing, these bikes would still be dominating Baja today!

I am walking in your exact xr650r steps. I just bought an Australian 2000 xr650r from an honest seller who I spend tons of time with talking about the bike. The bike I am most familiar with is my 2004 cr250r that has been built head to toe for the desert (I'm obsessed with Utah). I heard a lot of "rolling" noise in the top end of the bike (especially with my helmet on). Being unfamiliar with 4-strokes I bought the bike for a fair price. It's super clean; I just figured the rolling noise was inherent (the piston is like a Folgers can for God's sake). I promised to check the valve lashes before riding it.

These XR650R engines transmit a lot of noise.  My engine was relatively quiet (as an ex-heavy equipment operator, my hearing capacity is "relative", too) until I added the aftermarket metal skid plate.  The plate is terrific but it amplifies moving parts noise levels like a stethoscope or megaphone!  Scary but not indicative of any engine issues or worries.

Before I get into this, I must say that the bike ran GREAT when I rode it... a monster! Australian Model is a pure breed (aside from that lean main jet you were talking about).

Jetting could be normal if Aussie market.  They likely used the Euro or non-North America tuning.  Verify the jet sizes, you might be lucky here; at worst, an easy jet change.

I pulled the valve check covers off to check clearances. Hmmm, no clearance IN or EX... worried.

This can be deceiving if the auto-decompression system is still in place.  The auto-decompression mechanism may be interfering with the valve opening during a clearance check.  TDC must be atop the compression stroke...Make sure auto-decompression is not going on while you're testing the exhaust valve clearance.  There is little discussion in the shop manual about auto-decompression and valve clearance checks.  

My HotCams Stage 1 camshaft choice was more about eliminating the auto-decompression mechanism than higher performance:  Surprisingly, I got both and really like the manners of this camshaft for the XR650R engine.  Stage 1 tuning is just right—and plenty!

It had a K&N air filter on it.... I pulled the filter off in the light and I just about passed out. It was like a dirt wind tunnel. One thing led to the next I had the motor out of the bike.  

Deja vu...Another low-mileage XR650R with valve damage due to aftermarket filtration by a previous owner!  In fairness this is often installer error, as the XR650R filter is very sensitive to sealing around its edges.  The factory does a better engineering job in this area...I'm sticking with the stock Honda filtration system and backfire screen.

  1. Cam = done
  2. Rockers = done
  3. Piston = done
  4. Cylinder = done horizontal scoring at the top of EX side
  5. Valves = done, packed in and trashed
  6. Cam chain and sprockets were worn for typical wear and tear..
  7. Pictures of everything in the link below

Needless to say, I'm re-building the head and top-end. For me the next step is prevention. Questions like, "is the oil system working properly?" and, "is the jetting on point?" started popping up.... this is how I found your site.

The air filter is the main culprit in my eyes for obvious reasons (the air boot looks like a dirt wind tunnel).

The bike is uncorked: 

  1. open muffler
  2. open manifold
  3. main = 175
  4. pilot = 65S which is weird
  5. needle = 53E on the second to the bottom position

I live in good 'ol Colorado. I ride here and as far south as Moab so 3000' to 9000'. I picked up a Stage 1 Hotcam, which will be its only modification besides being uncorked. 175 seems a little fat. My main concern is the motor's safety when I take it to the desert. What main size would you recommend? Should I find a 68S pilot and whats up with my clip position? Probably just the old rider tuning?

Sounds like sea level jetted for back country or enduro riding, or sustained highway speeds, it was likely too fat during roll-on or mid-range, and the tuner leaned out the pilot to compensate for the richer needle position.  Or maybe the 65 pilot was slightly lean, and he raised the needle one position for more flow.  The 68S and 3rd clip position is well-tested as a benchmark tune.  

Here, for those interested, is what the 3rd clip position looks like courtesy of U.K. XR650R enthusiasts:

http://www.xr650r.co.uk/service/carb/17.jpg

Visit these XR650R enthusiasts at the U.K.  By coincidence, their choice of main jet is 172!  "Great minds?"  Check this out:

 https://www.xr650r.co.uk/service/carb/carb.shtml

You'll be thrilled with the HotCams Stage 1 camshaft choice, stable idle, incredible torque from bottom to roll-on and through the mid-range.  Unlike your CR250R, the XR650R engine does not like to be wrung out.  I do not have a tach but sense a redline of 6200-6500 rpm maximum, a somewhat meaningless figure anyway, as you'll always be upshifting way before this point. (3,500-5,500 rpm is typical even under brisk acceleration).  You'll see my point when you ride again.  I've ridden 650 twins and thumpers since the 'sixties; in my experience, the XR650R has the best roll-on throttle response.

I don't run an aftermarket pipe, and my tuning reflects the HRC tailpipe cap, open/round intake manifold grommet (49-State stock) with the larger tailpipe opening being the only exhaust mod.  This is essentially the non-North America OEM tailpipe cap, you may already have it as "uncorked".  

Note: Check out my tuning details at both the forums and also at the magazine site.  Probe at the search box under "XR650R".  There is also the Vimeo On Demand rental how-to if you need hands-on insight into building the top end.

If you will..can you give me some advice on the following?:

  1. What jets would you like me to run?

Let's begin with a comparison:  I live at 4300 feet and commonly ride to 7200 feet elevation.  I also take the bike to lower altitudes, typically 2,000-2,500 feet.  As I share at the forums and magazine coverage, I run a 172 main jet, 68 (no "S" though that's not critical either way) and my needle at 3rd clip position.  (The 53E needle is common as a needle replacement.)  I am purposely pushing the outer limits for richness, and a 172 main is on the rich side but tolerable.  My tuning is geared toward lower altitude survival and not having to change jetting for occasional riding below 4,000 feet elevation.  We know from history that Honda tortured these engines to meet North America emissions, with ultra-lean main and pilot jetting that, on the one hand, shows the leanest jetting this engine can tolerate at sea level and also what might well be acceptable jetting at the higher reaches of the Colorado 'Fourteeners.

So, from experience, I am willing to run what Honda considered "normal" jetting (for the non-North America market) as a baseline for sea level tuning.  In truth, I could readily run 165 or even 162 jetting at my 4,000-7,500 altitude range, and likely be safely jetted down to 2,000 feet elevation.  Were I running with Johnny Campbell on the beach in "Dust to Glory", with my type of engine build and not his, I would probably run a 175 main.  My current 172 would likely do fine.

I compensate for the slightly richer looking spark plug and tailpipe readings with a Pulstar spark plug, not a hotter range but a zappier spark with longer duration.  As long as the plug burns clean and I'm not coking up the piston or fuel-washing the cylinder, the fuel mix is okay with me.  Richer mixtures cool the upper cylinder, and in my view, right up to the threshold of plug fouling, fuel washing or carbon buildup is an optimal place to be.  Foul the plug, however, and you have the equivalent of 20 degrees ignition retard. (Timing advance equals more power; the timing advance limit should be the point just below detonation/ping.) Less timing advance means a loss of performance.  Make sure the spark plug burns clean and can fire properly.

For your riding, especially at higher altitudes, a 165 main jet would be plenty, certainly not harmful, as a place to start.  The camshaft should tolerate a 165 jet.  My idle through roll-on suggests that the 3rd clip position as others describe, and not the second, works best.  (If your PO was very heavy or carried hefty loads or two-up, the 2nd position may have helped with transition performance.)  Under conditions like snail-paced single track or open desert high speed forays, my tuning works well.  I'd use this at Moab or Southern Utah, Salt Lake, Grand Junction, Denver and even a bit higher.  165 would raise the altitude bar, I'd be willing to say to 9000-9500 feet for short periods.

      2. float height options (I have no idea)?

STOCK, out of the factory shop manual specs!  The Keihin is hypersensitive to float height.  I've never starved my engine under normal rpm operation.  I did run the bowl too low, one time, while showing a CRF450X rider what the XR650R "would do".  My approach was an attempt to match rpm ranges, which are not comparable.  The XR650R should be upshifted and not flogged.  In fact, I'm always looking for a "6th gear" with the stock sprocket tooth counts.  Rely on this engine's massive and quick rise in torque, not the rpm peak, and your fresh engine will last indefinitely.  When in doubt, UPSHIFT!

       3. should I ditch that darn K&N? What's the most bomber air filter option?

As you will discover in my magazine and forums coverage of the XR650R and its survival needs, the key is making sure that the filter seals at its edges and does not allow dirt to pass around the filter.  That's what happened when the PO of my bike added a popular aftermarket filter that allowed the engine to suck dirt around its edges.  The good news is that I built a bulletproof top end in the wake of pitted intake valves and slight Nikasil damage.  The L.A. Sleeve work was outstanding, especially the barrel sleeve upgrade that I requested with its chromium-moly iron alloy.  

Another concern with high flow air filtration is inability to filter out debris.  Micron filtration should be comparable to the factory benchmark or better.  Frankly, I restored the filter to stock, including a new fire trap screen that makes the edges hold firmer; this assures that the engine is protected.  I have never "run out of air" at the normal rpm ceiling, and the performance is plenty.  

       4. I've heard about a needle o-ring, what's the deal with that? Would you recommend it?

This is likely the O-ring that is stock on the idle/needle jet.  It gets lost or damaged, which causes a leak and erratic idle.  Use the factory parts schematic to identify your carburetor parts.  (Schematic can be found in a service/shop manual or online from a Honda parts sources.)  You'll see the O-ring and washer on the idle screw.  Lay out all of your carburetor parts for an accounting.  If this is the O-ring you describe, it comes in the $20 carburetor rebuilding kit from Honda.  These kits are rubber parts only and, well, overpriced.  Good news is the fuel-grade, appropriate materials in the rubber. 

       5. What plug have you seen work best in this bike over the years?

If you review my XR650R coverage at the magazine site and forums, the Pulstar plug comes up.  If tuned properly, a Nippon-Denso or NGK works well.  I use NGK, the OEM replacement heat range plugs.  Tuning is key to spark plug function.  I have crawled in rocks (always rocks smaller than skid plate bashing height) with the XR650R engine running steadily from idle to 1500 rpm.  Same tune allows wide open throttle thunder in the desert...

Here are some off topic XR questions:

  1. I'm running really wide bars, is it okay that I run the throttle hand grip upside-down to afford me more slack?

Does this reverse the rotation?  I would rather build a longer cable(s) to provide a layout similar to stock.  You don't want the cable to get snagged and raise engine speed unexpectedly.

     2.  I'd like to run some strong lighting for night desert riding, what direction would you point me in lighting wise?

Baja Designs and others have advanced LED lighting.  I'm running PIAA on the Ram truck and did a video recently that's at the magazine site.  Lower amperage, higher brightness and safety, this is worthwhile technology.  Try PIAA and Baja Designs.

     3.  I'm using the following service manual link. https://goo.gl/0FDef2 I believe it's universal. What do you think and if you think I need to order one, where would you recommend I get a Australian service manual?

I bought a factory manual download similar to this for $12.  It is non-U.S., which I like, as my bike was a 49-State U.S. model that did not have the California emissions parts included.  49-State bikes are closer to your Aussie type, which fortunately in your case, was a "factory dual-sport".  My cycle required a Baja Designs conversion to match what you have stock.  Get the overseas shop manual coverage, it will have your wiring schematic, factory lighting, charge circuit and other needs.  See whether the manual you share has that type of coverage.  Check the XR650R models covered.

If you ever want to plan a ride out in the desert, I'd be happy to coordinate.

Which deserts do you ride?  I've considered bringing a bike to Moab since 1995 and invariably wind up preoccupied with Jeep and other 4x4 filming chores...

Also, check this out for for an XR650r reference: http://teknikmotorsport.com.au/Honda-XR650R-Suspension-Mods remove choke butterfly and 165 main? huh

The 165 main is not a bad idea for overall riding.  If I make a change, 165 would be a conservative first test.

Photo's of everything here: https://we.tl/klDz7P3CGl

Feel free to post any or all of these photos here at the forums...We have the Photo Gallery—or simply start a new topic!  Your bikes show exceptional care and set a precedent for others...

Thanks!

Costa

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Hi Costa,

Good that you've found Moses and this site! My revamping of a trashed 2002 XR a couple of years ago would have been much more difficult without. I still have the bike and it's still going strong. These days, I don't often get the chance to ride it, but I'll make an effort to do more.

As Moses says, these bikes are pretty fun despite not being the latest tech.

To comment on some of the questions you had - GO WITH WHAT MOSES SAYS. He's da man!

I had mine set up for riding at between 1,000-2,000 meters in Burundi (Goggle it and/or look for a YouTube channel called Birds View Burundi to get an idea of what it's like). So I was running uncorked, 170 main and 65S pilot (at least I think it was a 65S...) and the clip in the standard position. It ran great. Really great... after I figured out how to get the valve lash set that is. With stock cam it's a real PITA (and does a serious number on your knuckles. But that's a whole 'nuther story). 

But now I'm in Nigeria - at sea level. So I've gone back to the original 175 main and 68S (again, I think it's a 68S...). No other changes. Given the sea level altitude, I had expected a little boost in power, but whether I had just forgotten the kick this bike has or what; the ooomph it now has is really amazing!

To get this bike's motor back into shape, I pretty much followed Moses's video on the top end rebuild to the letter - except for the cam. My piston and head looked way worse than yours, but my stock cam and rockers were fine. Valve job with new valves, new seals and new intake guides took care of the head, and a resleeve (by LA Sleeve) with new piston sorted the rest. The cause of the problems with my motor was running with no air filter (yep!) at all for an untold amount of time before I got my hands on it.

I had to do a lot of other work, but nothing out of the ordinary for a bike that had been abused and messed with by countless hamfisted shade-tree mechanics who knew very little about mechanics. The only thing remaining that's on the list is the suspension. It's probably pretty worn, but I'm not that great a rider so I probably wouldn't benefit a whole huge amount.

Yes, the engine makes some mechanical noise compared to some of the other stuff I've ridden. Seems like the noise comes from lower down in the engine. If I pay attention, it sounds like farm equipment, and makes me wonder. It's not getting worse, but whether there were a problem or not, I'm not in the mood to take this thing apart again - and much less the bottom end! Since I'm always using earplugs I don't let it bother me. :)

The air filter thing is a problem. I've never seen the stock one, but the aftermarket I have can't be much different. It may not fit perfectly at some of the edges, but I figure it's good enough if I keep it oiled & clean. There is surely something better than the stock one out there.

As for oil and changing it goes, the manual you posted the link for is the best set of instructions. There are 3 filters - the main paper one and 2 screens. I don't think I've checked my bottom screen, but the one time I checked it, the one in the frame drop tube was seriously dirty with metal in it. I'll definitely look at it again on the next oil change. Since the rebuild, my bike doesn't seem to use any oil. 

Good luck with yours!

David

 

 

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Hi, David!  Delighted that you shared this info with Costa...Nigeria should have plenty of riding room.  Very pleased that you still have the XR650R.  Costa suggests riding together in the desert...If you're headed for the West or Southwest U.S. with your bike, it would be fun to gather and celebrate our icons with a ride!

Looking forward to more news about Africa and your riding...

Moses

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  • 10 months later...

Hey Gents,

I've been meaning to get back to you guys with some results...

A local shop re-built the head completely and I installed a stage 2 hot cam. I set the lashes for the new cam and reassembled the bike (new top end and cylinder also). After a break in and then about 150 miles I noticed the intake rocker shaft (visible from the exterior left side of the motor) had some rotational movement. I sent a video over to the shop that built the head and they wanted to take a look. After their disassembly and inspection they said their work was done correctly and my work was done correctly, but the top end is smoked (cam is done, and rockers are done and worn). They said lack of lubrication.

So thats where I'm at! Might have to sell the bike for cheap.

Hope you guys are well,

Costa

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Costa...Sorry to hear you had these troubles.  Oil starvation will do this.  Did the lower end starve or was this strictly the cylinder head?  Your bike looks great and should be a candidate for a proper engine rebuild.

If you do want to let the bike go, I'm certain you will find a buyer willing to do the engine work necessary.  These XR650R models continue to hold cache and value.  I would not "give it away", be forthright with the buyer but expect a reasonable return.

Not sure where your market is located.  In the U.S. Lower States, these cycles typically fetch $2500-$5000 depending upon history and overall condition.  Rare, limited use cycles that have been in "storage" often bring $6000.  I would think you could get $1500-$2000 in current condition if the rest of the bike is in top shape.  

I bought my bike for less than this but had no idea what the engine needed, and it did not run.  I immediately rebuilt the top end of the engine, rebuilt the carburetor, mounted new tires and restored the air induction system.  The bike had an alleged 1000 total miles of use since new.  The aftermarket air intake filtration had not been sealing properly, which wiped out the intake valves and damaged the rings and Nikasil cylinder.  The chassis was in excellent condition, which substantiated the mileage claim.  

If you have the "history" on this cycle and other selling points, I would certainly ask $1500 or more as a starting point.

Moses

 

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Moses,

Thanks for the response. I'm in Michigan now, I'm not sure how the folks in this area value these incredible bikes. I'm not in a hurry to sell, so I'm sure I'll find a worthwhile buyer. Thanks for the good word on the value of these cycles!

Costa

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Costa...Best of luck with the bike, whether you sell it or not.  These machines have a following, and Michigan is no exception.  Folks will ship and travel distances to get an XR650R.  I increased my search radius to 500 miles when I sought my bike, just got lucky when one popped up in our area...Let us know how this turns out.

Moses

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  • 3 months later...

Hello Moses, its been a while, and my Bike is working so good.  Thank you for al your insight. 

I was wondering if you installed a header on your bike. 

Also, I am about to change some bearings. Could you tell which is the best brand, OEM, Pivot Works, All Bearings, Moose Racing, etc.? Please tell me the tools you use for the following:
1. Steering stem
2. Wheels
3. Swingarm
4. Shock

 Thank you,

Arnaldo

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Arnaldo, I'm very glad that you're happy with your XR650R!  Mine is a "keeper", too...You have to own a 'Big Red Pig' to appreciate its many virtues.  These bikes are so flexible.  With some finesse, we can single-track, ride open desert at high speeds (its original purpose), or find ourselves grinning as the asphalt blurs beneath the foot pegs.  Not too long on asphalt, though, unless you soften the rigid seat...I'll likely do a Seat Concepts re-padding before next Spring.

I've not installed a header, though your Big Gun would be my choice.  They work hard at a quality product.  A header usually focuses on a specific rpm range improvement, the Big Gun at least on paper provides a wider band of gains.  Your experience and feedback here would be valued, starting a fresh topic with your impressions...I'm still stock header and exhaust system with the HRC type large outlet (uncorked).

The niche tools from Moose and Pivot Works look good.  Factory tools match up with the Honda Service Manual procedures for our bikes, though there are always improvements and gains from a well-conceived aftermarket tool.  I often improvise and make a tool, following the aims of a factory service tool; however, this can require fabricating and shaping the tool with a plasma cutter or other ways, MIG or TIG welding, finishing, etc.  I enjoy this, but you've got to be invested in the creative and technical side of "tool making".   Buying ready-made tools can prove cost effective if you value your time.

Consider buying or making any tool that prevents damage or unacceptable stress to parts.  This applies in particular to pullers and press tools.  As an example, for automotive gear work I use a Posi-Lock 208 puller (http://www.posilock.com/products/manual-pullers/manual-pullers) for its stability, safety and uniform pulling force.  The Honda has a lot of expensive alloy parts that can easily be distorted, bent or damaged by improper application of force.  (Think of the swing arm as just one example.)  

The rule of thumb for any motorcycle work is minimal use of force, just enough to get the job done!  Take your time and follow sequence steps carefully.  I use the  XR650R factory workshop manual for procedural guidelines.  Take this a step further, use good judgment and back off when you encounter excess resistance. 

A press can provide safe and controlled ways to remove and install bearings, seals and bushings.  Safely back up the parts to isolate the force.  I have a Harbor Freight 20-ton bottle jack press (current version shown here, mine is 20 years old and still going strongly:  https://www.harborfreight.com/20-ton-shop-press-32879.html).  I upgraded my press with a 20-ton air-over-hydraulic jack (https://www.harborfreight.com/20-ton-air-hydraulic-bottle-jack-69593.html) that offers relatively slow and controlled application of force. 

When questionable resistance occurs, I often use the air/hydraulic jack's hand pumping option to get a better "feel" for the resistance.  The next HF press modification will be a pressure gauge on the hydraulic system to monitor the actual force applied.  Never force parts, and always center the pieces carefully.  To reduce friction, I use Sunnen B200L Press Fit Lubricant on sleeves and bushing jackets during installation.

Tools are wonderful when used correctly.  Think in terms of restoration and preservation.  When you encounter too much force or resistance, stop and consider an overlooked step.  See my videos on Time-Sert® thread repairs, these kits can be spendy but well worth it for Honda and other alloy threads that go south.  Often, you're not only restoring threads and preserving an expensive casting, the Time-Sert® upgrade actually provides a significant improvement over a factory thread design.  The first three video links at this page are each helpful and focus on Honda XR650R work:  http://www.4wdmechanix.com/?s=time-sert.

If you have the time, share your pending work on the XR650R.  Start new topics on your experiences.  Cell phone photos are great these days and always welcome here!

Moses

 

 

 

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  • 2 years later...

Hey Moses. Hope this message reaches you, as it’s been almost 3 years since the last post. I have a 2003 XR650R uncorked with an XR’s only full exhaust and k&n air filter. I installed a hot cam stage 2 and had issues with it (would randomly die at idle and idle would start to race when engine is warm). I checked valve clearances, engine compression, float height, made sure throttle cables weren’t binding, pilot jetting, checked air cutoff diaphragm for holes, to no avail. I ended up changing it out for a stage 1 hotcam, and the stalling issues are gone. The idle is still a little erratic,  it is much better than before. Any idea what could have caused this? Also, do you think my jetting is correct as my last XR650R felt a bit more torquey in comparison. My previous XR had stock cam, full fmf exhaust, 175 main, stock needle on 3rd clip, and 68s pilot. My current bike has stage 1 hot cam, xrs only full exhaust, 185 main, competition b53e needle on 3rd clip, and 68s pilot. I’m at sea level by the way. I’ve searched the Internet far and wide for answers, and it seems like you’re very knowledgeable on this bike. If you could provide your input I’d greatly appreciate it. Thanks

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Hi, prubing...In looking over your data, the 185 main jet could be on the rich side.  (I'm not clear about the elevation where you run the bike.)  Read the spark plug coloration after a brief wide open throttle pull and immediate shut-down.  If too rich, try a 180 or a 175 main jet again.  Read the rest of my comments before running this test or re-jetting.

Any performance cam will have more valve overlap, and this can impact idle.  The Stage II cam proved the point.  I'm happy with the Stage I and anticipated that the Stage II would be too much cam for my usage.  A Stage II would be an open desert racing profile; for an XR650R, restarting would be like the "Dust to Glory" issues at the pit stop.  Great camshaft for top end power, not a choice for my variety of riding conditions, ranging from chugging on a trail, through stream beds or in the open desert.

Other issues with idle and especially a speed flare-up would include an air leak.  (This can also be a vacuum leak.)  Unwanted air available when your jetting is too rich (pilot or main) will cause speed flare-ups.  Two things affect idle speed:  1) available air, which is normally available only via the slide bore and 2) available fuel.  An air leak could explain why this problem was worse with the Stage II camshaft, which wants to draw more available air/fuel.  The Stage I camshaft does not have as much lift or duration, i.e. it has less valve overlap. 

Also, these XR650R engines do not have variable valve timing like modern automotive performance engines:  Valve timing is fixed whether the engine tries to idle or is running at wide-open-throttle (WOT).  Without variable valve timing, there is no way to compensate for a hotter camshaft profile.  The engine can run great at WOT with a compromise at an idle, the ongoing challenge of performance camshafts.  In the muscle car era, we tuned engines with hot factory and aftermarket camshafts.  In some cases, the "normal" idle rpm to keep the engine running was 1400-1500 rpm.  The same yardstick applies with an XR650R, which with a stock camshaft calls for a 1400 +/_ 100 rpm warm idle speed—as high as 1500 rpm with a stock camshaft at idle

Check for air leaks.  This is simple enough.  With the engine idling at a steady speed, spray a light mist of lower volatility lube like WD-40 around the air tube from the filter to carburetor, the manifold to the carburetor flange, the manifold to the cylinder head, at vacuum hoses, crankcase ventilation devices (CA emissions devices in particular) or at the sides of the carburetor body.  This will turn up an air leak.  The engine speed will change if the spray is drawn into the induction stream at any of these points.

Inspect carefully for a worn carburetor throttle slide or slide bore;  this can be a deceptive air leak source.  Slide wear was a notorious problem when I tuned British motorcycle engines with Amal concentric carburetors.  My '69 BSA Rocket III 750 triple had three carburetors, three breaker point sets and three ignition coils.  At least the XR650R only has one of each. 

Moses 

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Hey Moses. Thanks for the reply. I am running at sea level. The bike seems to run better on a 182 jet and I am waiting for the 180 to test also. I also changed the pilot to a 70 since it’s starting to get colder here in NYC. There seems to be no air leaks when I spray with WD-40. I will inspect the throttle slide. I readjusted the floats for a second time, as I heard these bikes are very sensitive to float level. It was maybe a millimeter or two too low. The bike seemed to idle much more consistently after this and didn’t speed up. Could this of been the issue? I’m wondering if the bike is more sensitive to float height with the cam, as it may have changed the vacuum at idle. 
 

Phil

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Hi, Phil...Float level is always important.  The more significant change you made was the pilot jet.  Apparently, the engine needed more idle fuel to stabilize.  Again, this could be due to an air source somewhere. 

Try spraying around the plate cover above the slide.  There is an O-seal around the inside of this plate.  This is a test for leakage at the plate, which would be a direct, additional air source.  If air leaks into the slide bore from the plate, you would be turning down the throttle/idle screw and lowering the slide to compensate for an overly fast idle.  In doing so, you drop the needed into the pilot jet and "starve" off fuel. 

A worn slide, slide bore or worn throttle shaft can each be unwanted air sources on this Keihin carburetor.  Another often overlooked source of trouble with these carburetors is the Air Cut-Off Valve.  If sold at New York, your bike is likely 49-State without California emissions devices.  Be certain there is not a leak at the Air Cut-Off Valve and that each piece, including the diaphragm, is in good condition and installed properly.

Of course, the Stage II camshaft impacts tune, but rule out these other possibilities.  I'm not a big fan of this carburetor; however, they do work reasonably well when new.  It's worth restoring carburetor functions to see whether that solves the problem.  Fattening the pilot flow may be part of the Stage II cam tune;  however, make sure you're not just compensating for an air leak.

Moses

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