32 posts in this topic

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David, that's not only felt, it looks like a bona fide dust seal!  If so, the seal is a good way to protect against air leaks and to keep dirt out of the throttle shaft bore and engine.  When you're able and willing, check for an air leak here.  From what you have described elsewhere, this is probably not a dominant issue.

 

As for the auto-decompressor, the right side (brake pedal side) of the engine is the exhaust valve that has a built-in arm/link for the auto-decompressor cam.  The tip-off is that the manual lever (handlebar lever decompressor) is at the left side of the rocker box, and this actuates (unseats) the left exhaust valve.

 

So, you're spot on:  The auto-decompressor valve is the one out of adjustment now.  And now I'm beginning to suspect that the auto-decompressor is "sticky" or acting up.  You've done such good work on the rest of the engine and tune, including the carburetor, that there's little chance of a flaw elsewhere.  A large clue is that the engine ran well then suddenly acted up and fouled the plug on both occasions.  This could readily be a sudden loss of compression from the decompressor unseating the right side exhaust valve.  The good news is that the right side exhaust valve (if adjusted anywhere near correctly) will not stay unseated long enough in the valve's normal opening cycle to shove a valve through the piston crown...

 

If this is the trouble, strive to free up the auto-decompressor short of my camshaft change solution.  Sticky could mean sludge or an oil flow issue in the mechanism if the springs and other hard parts are still okay.  The oil plunger plays a role with the auto-decompressor function...

 

Was this engine's oil maintenance like the rest of the previous owner/operator's maintenance?  If so, it's likely due for a serious oil system flush.  If you suspect this possibility, we'll put our heads together on a safe and suitable flushing method for this dry-sump engine.  Also, have you changed the oil filter yet, and if so, how "dirty" was the cavity around the filter?

 

A possible solution would be a high "detergent", high lubricity oil.  If you haven't drained that first fill yet, consider whether the rings have had long enough to seat.  No blue smoke and strong compression, both accelerating and decelerating, would be clues.  (Actually, with my XR650R engine, there was never a sign of blue smoke or any sensation of incomplete ring seal from the first start-up.)  After flushing the system thoroughly, consider your synthetic oil if the ring seal is now sufficient, and let's get that auto-decompressor to at least do what Honda intended.

 

The reason I chucked the idea of using the auto-decompressor was the unpredictable jamming of the kick starter mechanism and erratic operation of this device during my first days of futilely attempting to kick the engine over.  (This was when compression was absent, and I had not yet run the leakdown test that led to the top-end rebuild.)  Without belaboring the point, that was enough "auto-decompressor" for me.  Since the only possible advantage of this device is kick starting without thought or special measures, I opted out of the strategy.  Again, thanks to the '69 BSA Victor 441cc experience with 9.5:1 compression, I did know how to use a manual compression release for starting a high compression thumper.  The lesson apparently stuck, and more than 40 years later, I can kick start my Honda XR650R on one or two kicks (hot or cold so far, winter's around the corner for that test), using only the manual lever and no auto-decompressor.  I'm delighted with the Hot Cams 'Stage 1' solution.

 

If anyone is interested in booting the auto-decompressor camshaft on a Honda XR650R yet fretting over whether the engine can start readily without it, I'd be delighted to do an HD video on my starting technique.  It's highly effective and reliable, hasn't failed me yet!  We can start a new topic on that subject...

 

Moses

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Posted · Report post

Hi Moses,

 

I guess you could say dust seal. It wouldn't stand up to any serious vacuum if it were present (even in good condition). But whatever the case, my woe has has come down to valve adjustment - not carburetion. At least so the 30 odd Kms I did today would indicate. 

 

After turning the engine over several times this morning, I never got the right side exhaust valve to loosen up. So I figured that perhaps it was like the others and just had a moment of rambunctiousness at the specific moment that I had adjusted it and the other valves before. We'll blame it on a full moon. So I simply adjusted it again (this particular one is a pain in the access department...). I didn't even bother to touch the carburetor since I figured this has to be it.

 

When I think back to when the engine started messing up yesterday, it was immediately after being subjected to stop and go traffic and then a good blast when I untangled myself from the mess. Something must have just gone "click" in the autodecompressor and tightened that valve up.

 

Anyway, to end the suspense, it ran fine all day today after the adjustment. There was one scare when power abruptly fell away and the motor was popping and snorting - but it was that I had simply run out of gas  :huh:. Pretty much right in front of a gas station.  :D 

 

Now that the engine runs regularly, I can make some other observations:

 

  • I am accustomed to riding multi-cylinder big-bore sport bikes while wearing earplugs. Today's ride on the BRP was without plugs, and I am a bit surprised by the mechanical noises coming from the engine - it's like riding a tractor. I don't think anything is wrong, but it is definitely not the sewing machine smooth of a CBRXX Blackbird or my buddy's ZZR 1400! On the other hand, there is plenty of good noise coming from the intake and exhaust. For the moment I will forgive.
  • It starts easily (warm or warm-ish), so long as you do the trick of pushing a little past TDC on the maunal decomp, and then kicking. First time every time unless I forget to return the kill switch to "run" (oops!). All the same, the kickstarter sometimes skips a tooth and that has me a little worried that it'll get worse.
  • The power is pretty good - but not mind blowing. The torque, on the other hand, is fun to play with. Again, I guess it depends where you are coming from and what you expect. This will likely improve as the break-in progresses and I increase the revs.
  • The power/torque on this bike is apparently now much better than before as the clutch is giving signs of not being able to handle the brrrrraaaaps I'm giving it - even at the somewhat modest break-in revs. While it's not slipping in an obvious manner, I don't think it's Moses-style wheelspin like we see on the forum video.
  • I wish it had an ignition key. Parking in town is a little disconcerting - even if this is not a place where things like this get stolen.
  • I really stink at riding a dirt bike! I hope this is something that will also improve - but with out the "break" of break-in.

As far as jetting is concerned, I think I might have some more work to do in order to perfect things (but it is not at all bad as-is). Acceleration is without hesitation throughout the rev range, but I get a fair amount of burbling and popping (not the classic backfires though) on the after-run, and on downhill stretches. It's a bit more than I think there should/could be. Although it sounds cool, I'm suspecting it's a sign of inefficiency. I have not fiddled with the mixture screw again with the bike running correctly, so the drill from the manual may have an impact on the above condition.

 

I seem to have a momentary surge when shutting down from higher revs. It could be related to my impression of potential clutch slippage (meaning the clutch is just catching up to the rest of the bike), or it could be something that jetting will relieve. It's not major, so I'll probably live with it for a while while I learn the bike more.

 

Whatever the case, I'm extremely happy to have it run properly for a full day. It was starting to get frustrating!!

 

D.

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Posted · Report post

Good work, David!...Welcome to high torque and no need to "wring out" the rpm, this is a thumper!  I would do the idle mixture again, and there are lots of references to the deceleration valve issues at the carburetor.  Fortunately, I'm not experiencing them.  I am conscientious about rolling off the throttle smoothly when possible, avoiding abrupt closure on decel.  This is instinct for a 4-stroke thumper.

 

I would check the clutch adjustment, I'm sure it's been overlooked in the past.  Don't stop at the handlebar lever free-play, take it a step further and make sure there's a slight amount of play at the clutch lever atop the engine case.  This adjustment often gets ignored, and the clutch can end up slipping needlessly—and wearing out prematurely!

 

You're doing thorough, good work, and this engine should be running like a top soon!  We'll discuss dirt riding habits as you gain some miles on this beast, certainly room for that new topic!  Would be great if our paths were closer, the best way to learn dirt is to ride in the company of others with experience.  This is an altogether different paradigm than asphalt, steering with the throttle more and taking dirt corners on with an entirely different approach.  Best advice I can offer at this stage:  Keep a lid on the speed and throttle as you learn the ropes and how this bike handles.

 

I'm constantly referencing the BSA Victor 441, and for the sake of those who wonder about these anachronistic reflections, here's a well done article by an insightful author, published five years ago in Motorcycle Consumer News.  The online site made the article available as this download PDF: BSA 441 Victor.pdf.  Enjoy this traditional thumper—I sure did, despite its vertical, twin coil-over rear shock absorbers and miniscule front fork travel!  Let's hear it for our mono-shocks and 'Pro-Link', our long travel front forks and disc brakes... 

 

Moses

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Posted · Report post

Hi Moses,

 

Didn't have a chance to ride yesterday, but took it to town today to try to resolve the non-clip masterlink and the busted chain adjuster bolt in the swing arm. I've done in total about 90 km since the top end rebuild.

 

It's interesting/frustrating/par for the course that when I look at the fora on the XR650R, every problem that is mentioned about this bike is present on mine... Of course there was the overheating, then there was the top-end problem that we've discussed at length, then there was the right side footpeg (took a Helicoil to sort), the chain adjuster bolts, the kickstarter bolt, ad infinitum...

 

And then there's things that I've not even touched like the swing arm bearings, the shock linkage bearings, the rusted spoke heads, and so on. Aside from the rear wheel being a minefield, I've noticed some play in the swing arm and rear shock, but I'm not gonna go there yet. That's yet an uknown and this beast is starting to look like a money-pit. Better enjoy some riding first.

 

Clutch is still iffy even after adding more free play to the cable (though it might be a shade better than day before yesterday - hard to say. Question: replace steel and friction and springs - or only friction and forget the rest? And what's the part number of the updated release bearing?

 

For the rest, I managed to get the rusted chain adjuster bolt out - after failed easy-outing with ever increasing sizes, and then having to resort to drilling it out with the intention to Helicoil. I actually found a supply of those (Chinese) in a tool shop run by a Russian (!), who also happened to have a portable hydraulic press with which we totally mangled the non-clip masterlink - now permanently on, or off limits... (à la Chernobyl). 

 

Anyway, just getting home, I was able to do the first WFO pass and plug chop - in 4th? gear. Uphill, so I think it's a valid chop. I've attached the photo (and just for fun I've included a photo of the plug that came out of the bike before the top-end rebuild - it's a little crusty). As you will notice, the new plug has got (in my opinion) an ok looking electrode, but the body surrounding is it a bit black. My immediate suspicion is that this is from pretty good main jetting (with the 170), but overly rich slow speed (65S) and perhaps even idle circuit. I'm at about 3,000 Ft, and most everywhere I will go from here is higher (up to about 7,000 ft max). Temps are in the 80s here and going down to the high 50s for a low at the highest altitudes.

 

I've not done the mixture screw adjustment yet, so this may have an impact. Your thoughts?

 

Tomorrow I'll flush the cooling system (with locally-sourced radiator flush made in UAE). I will also do the mixture screw adjustment.

 

D.

 

 

 

 

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Posted · Report post

David...Obviously, your bike had been ridden hard and put away wet as we say at horse country.  However, you've weathered the restoration to this point and have too invested to turn back.  Riding the beast in trouble-free form will be your ROI. 
 
The master link fiasco must be frustrating.  There is a tool, not expensive for this chore, and the creative use of a relatively inexpensive chain breaker can sometimes work here.
 
Long before I found my motorcycle, I also combed every XR650R forum for details on the idiosyncrasies of this model.  Typical of the internet culture, we each end up spewing the same "authoritative" findings.  Inspecting everything within reach and view, I found that my bike's chassis already had the litany of upgrades like the improved right side peg hardware.  However, like your bike, I've yet to confirm whether the clutch guide bushing has been upgraded.  Though I've rationalized that it likely has, I would like to inspect or replace this part when practical.  Meanwhile, since day one running, I've hedged my bets by intentionally not stressing this part.
 
Perhaps you have read the same dozen rehash references I did.  Apparently, the problem by design was lack of lubrication between this bushing and the shaft, resulting in potential bushing seizure under bizarre circumstances.  The accounts I read suggested that you'd have to rev the engine excessively with the clutch lever pulled in.  One example was fording a rock strewn stream and trying to keep the motorcycle moving.  In any case, if you do clutch work, it would be prudent to replace this sleeve/bushing (CLUTCH GUIDE/OUTER), especially since the cost is negligible.  The sleeve bushing supports the clutch basket and can seize on the shaft from lack of lubrication. 
 
Along with this suspect bushing (few superceded items like this exist for the XR650R) comes the caveat that if the bushing hasn't caused trouble yet, it may never be an issue.  From the same rumor mill comes speculation that once past the wear-in point, though lacking the additional oil groove of the replacement bushing, this early model XR650R bushing seldom fails.  (If so, my guess is that slightly more oil clearance after wear-in may lubricate the bushing better.)   In any case, given the cost, if you're doing clutch work, by all means replace the sleeve/bushing.  Here is the correct part number for the superceded part:
 
GUIDE, CLUTCH (OUTER) Part Number 22116-MBN-671 (Less than $15 U.S. by mail order, plus freight.) 
 
Here is the original, failure prone clutch guide part number, make sure you do not get this piece: GUIDE, CLUTCH (OUTER) 22116-MBN-670
 
The clutch-related item you may be considering is the ball release bearing, another relatively inexpensive and wise replacement part:  BEARING, RADIAL BALL Part Number 96100-60010-00  (Less than $10 U.S. by mail order, plus freight.)
 
As for the clutch work, when you take that initiative, I'd definitely replace the frictions.  The steel plates are iffy, I'd want to look them over for bluing and any indication of heat damage or warp.  If steel plates don't show either, the frictions might be enough.
 
The spark plug looks rich, though not to the point of gasoline fouling.  It took a while to reach this coating level, so if you were riding primarily on the slow speed jet then suddenly ran the WOT and chop, you'd still have a blackish plug like we see here.  Spark plugs are relatively cheap, and now that you have the bike in good working order, I'd install a new plug and do the WOT/chop test immediately after the first engine warm up.  Spark plugs are temperamental when they have been fouled and then "cleaned".  The only thorough cleaning is blasting, and this can be dangerous; blasting media can damage cement or get stuck within the plug then dislodge in the cylinder later.  In my early years as a light- and medium-duty truck fleet mechanic, spark plug blasting was popular.  Worth noting, engines had iron cylinder heads and blocks at the time.  (Compression ratios on the older engines ran 6.5:1 to 7.5:1 during the heyday of spark plug cleaning.)  On this subject, here's an insightful guide for cleaning aircraft spark plugs:

 

http://www.tempestplus.com/Portals/0/PDFs/MaintenanceandService/Sparkplug%20Cleaning%20The%20Right%20Way%20081412.pdf

 

From these findings, I can't condemn the slow jet or idle mixture without riding the motorcycle and controlling the throttle during the tests of each circuit.  There are specific throttle openings for the idle, the transition to the slow jet and the main jet.  I doubt that 3000 feet elevation would require much, if any, jet changes, and this is Honda orthodoxy.  Typically, the turn point is 5000 feet or higher.  As for taking the bike to 7000 feet, you would distinctly run rich there if the current spark plug reading is accurate.  I'm not convinced that it is, though.  You can tell more by riding the motorcycle.  How does it feel at precise, steady throttle positions?  Are you experiencing specific problems?
 
Note: I'm about to test a new spark plug design, the Enerpulse Pulstar.  I purposely ordered plugs for both XR motorcycles and the Jeep XJ Cherokee 4.0L.  What caught my fancy was a press release citing a Ford GT that raced recently in Europe over a course that goes from sea level to high elevation.  The engine produced more power without reacting adversely to altitude.  I'm curious to see how this plug "compensates" for normal altitude enrichment in a carbureted, single cylinder engine.  I have surroundings much like yours for testing.  Will update...
 

Also about to install an Acerbis (Ah-Chair-Beez) 6.3-gallon fuel tank.  This is to offset the demands of the motorcycle's add-on weight and my compelling plans for taking this motorcycle to remote places, as much as 100 miles from fuel sources.  My XR650R motorcycle should deliver 35 mpg when I behave myself, and rumor has it that one can shove 7 gallons into this tank readily.  Allowing a 5 mpg fudge factor, that's still a 200-plus mile range.  Actually, I'm sensing that my dual-sport highway mileage might creep above 40 mpg, though this could be wishful thinking.  I need to put the big tank on before testing that theory.
 
As for your pending cooling system flush, make sure the substance does not contain abrasive silicates, and this applies to the antifreeze/coolant as well.  Honda recommends non-silicate ethylene glycol only, and here I did take their word.  In our favorite world of internet intrigue, I stumbled upon an XR650R engine photo that startled me.  Abrasive coolant had scoured out aluminum passageways and destroyed the water pump seal.  Be cautious here, this is apparently a touchy and delicate cooling system—with expensive alloy castings.
 
Moses

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Posted · Report post

Indeed, put away wet & dirty.

 

After my first ride off road, the clutch has held out - it might hang in there for a little while yet. I hope at least as long as it takes to get the parts. I'll probably stick with frictions and a new bushing. 

 

The bike is running well so I'm not going to bother fooling with the jetting again until I have reason to take the tank off  (my thought was to substitute the 65S slow jet for the straight 65 that came in the Moose kit to see what happens). 

 

D.

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Posted · Report post

David...With proper clearance at the clutch release now, you'll likely be okay for a bit.  The frictions do make the best sense if there's no shudder or roughness upon clutch engagement.  Shudder usually indicates plate warp.  Most plate damage is from overheating the clutch or prolonged operation with slipping frictions.  Sounds like you caught this in time. 

 

Don't forget to check the clutch spring free lengths.  49mm or 1.93" is standard, easy to measure with a caliper or even a detailed 6" ruler with the springs standing on a flat surface.  When you take the clutch apart, measure these springs.  Here are the specs you'll need for this job:

 

Honda XR650R Clutch Specifications from 2000 MY.bmp

 

 

The 65 would be slightly less flow than the 65S, though the 65 rating indicates they should flow the same.  This has to do with emulsification improvement with the 65S.  If you're okay with performance and there are no overt signs of rich running, I'd put some miles/kilometers on this machine and get the break-in handled and compression up to peak.  I would like that spark plug at least light grey instead of black, brown optimistically.  Again, the blackening could be from earlier fouling.  Use your intuition on this jetting, if the engine is responsive, smooth and not blubbering or surging, tune should be close.

 

What we're trying to avoid here is fuel wash of the cylinder from over-rich mixture.  Fuel wash and oil dilution take lubricant from the cylinder wall and lead to wear.  Short of that, slight enrichment is actually a good thing, it cools the upper cylinder.  Too rich is not a good thing, it fouls the plug and causes fuel wash and oil dilution.  Avoid over rich.  Always avoid too lean.

 

I'm thrilled that you're riding and learning the virtues of the XR650R!!!  We can open new XR650R tuning and dirt riding topics—and broaden our horizons!

 

Moses

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