Is the Honda XR650R Auto-Decompressor Worth Keeping?

[Moses Ludel]

Many of today's dirt motorcycles have electric starting, and this is a very good idea for the contemporary ultra-high compression four-stroke singles! For these operators, unless the starter fails to work, manual kicking has become a thing of the past...

Despite this trend, there are still many kick-start Honda four-stroke motorcycle engines that have an "auto-decompressor" start mechanism. This device, typically mounted at one end of the overhead camshaft, unseats an exhaust valves during crankshaft rotation.  The aim is to relieve compression as the piston approaches TDC (top dead center) on the compression stroke, only during kick start phase. Once the engine starts, the mechanism disengages the ramp/cam that opens the exhaust valve during kick starting. 

On my Honda XR650R engine, the OEM camshaft was still in place when I purchased the bike. The engine did not run, and repeated attempts to kick it over proved futile. Eventually, I ran a leak down test and discovered a considerable loss of compression caused by leaking intake valves. Despite this low compression, the kick starter repeatedly balked as if the auto-decompressor was stuck off.

Even with leaking intake and exhaust valves, the engine would not kick over easily. The auto-decompressor was stuck in the off-position and acting as if not even there! Large piston displacement gave a false sense of "compression".

The bike had set for some time, and perhaps this accounted for the condition of the auto-decompressor.  It felt like the mechanism was sticking in the released position, providing no decompression.  Even with the low compression from leaking valves, I found myself using the hand lever decompressor to "free" up the compression resistance and what felt like a jammed kick starter.

Note: Wondering why an engine with leaking intake valves would still be hard to kick over?  This is not hard to explain with the volume of air that this huge piston can displace, an overwhelmingly large amount compared to the amount leaking off from valve face-to-seat seepage. Given the kick start resistance, I never suspected worn, leaking valves.  In fact, all four valves had a fair degree of seepage.

By the time I committed to the leak down test that led to the upper engine rebuild, I had researched the XR650R engine.  I'd also had enough experience (i.e., cardio workout) with the auto-decompressor to seek an aftermarket replacement camshaft without the auto-decompressor.  I was not opposed to using a manual decompressor lever and knew from my first experience with a BSA 441 Victor how to find that special point, just past TDC on the compression stroke, where the engine kicks through without kicking back.  Part of my rebuild was the choice to install a Hot Cams Stage 1 camshaft.  This is a milder performance approach that provides more bottom end and midrange power—and a camshaft that eliminates auto-decompression.

I'm good with my decision to eliminate auto-decompression and am curious how others have made peace with the factory start mechanism.  Am I the only one whose auto-decompressor has stuck or jammed?  I could have rebuilt and polished the OEM auto-decompressor, as the mechanism can be rebuilt.  I opted out.  Is everyone else happy with the stock camshaft and auto-decompressor?

Please share your experiences here...An auto-decompressor is not unique to the Honda XR650R, they come in many forms and configurations, like the kick-start mechanism on my '84 XR350R, still a valve unseating approach, that has worked flawlessly and easily for three decades.  From the XR600R forward, the auto-decompressor attaches to the camshaft and has a one-way clutch mechanism.  How does that work for others?

Moses

[DavidEasum]

Hi Moses...My decompressor is erratic. That's probably why I had such a tough time to get the valves adjusted correctly. So when I start, I usually look for TDC and then press slightly through with the manual level actuated. Then I kick. If it doesn't start, I sometimes go back to the lever, but often not.

Whatever the case, the engine doesn't often kick back, and a slow prod through the travel of the kick starter will meet with only slight resistance on the compression stroke. But when it does get full compression, the feeling through the lever is pretty intense.

I suppose I'm not unhappy having it - I'm used to it.  I just need to take it into account for valve adjustment.  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.

http://mydomain.invisionzone.com/uploads/monthly_12_2014/post-290-0-13114900-1417600016_thumb.jpg

D

[Moses Ludel]

Textbook photo, David!  The tall screw threads are a clear clue that the auto-decompressor was still "on" when the right side exhaust valve was set.  Thread height should be somewhat similar when the decompressor is fully released before the valve adjustment...Your comments on the auto-decompressor are very valuable to others.

Do you use the manual decompressor lever, too?  Or do you simply kick the engine through repeatedly without having to fiddle with TDC?  How often does it balk as you describe?  Is this ankle jarring?

Moses

[Matt Bernhard]

Hey Moses, thank you for being so thorough with your xr650r videos. I just purchased a nicely optioned 2000 xr650r. The previous owner claims to have checked out the top end 3k miles ago. He said new oem rings were installed as well as cam bearings and a chain tensioner, because they were there. The motor does look like it has new gaskets as well as some sort of sealant around the head. The bike fires up easily enough and runs well. Almost too easily. I feel like the auto decompression is giving me a false sense of what a 650cc single should feel like to kick over. I am going to do a leak down test just to give me the satisfaction that the bike is in good running order. I'll report back.

[Moses Ludel]

Matt...To avoid inaccuracy or scaring yourself, I suggest backing off the valve adjusters enough to clearly seat the valves before running that leakdown test.  Still have the piston at TDC on the compression stroke, as the piston atop its bore here is the best point for measuring cylinder wear or "taper".  With the auto-decompressor, it's otherwise very easy to get a false reading from an unseated valve...

Here's some Honda XR650R fun, a ride I took two weekends ago at El Dorado Canyon.  For the record, the bike survived this outing without a scratch topside or bottom, I never touched a rock or obstacle, keeping both feet on the pegs unless stopped...

This supposedly "heavy" bike (add dual-sport equipment and be sure to top off the 6.3 gallon fuel tank!) never ceases to amaze me.  I'm a mechanical preservationist and almost left the bike home in favor of my single track, trail tested vintage (1984) Honda XR350R.  Thought I'd try it.   The day's riding ended up 179 miles of the Pine Nut Mountains, a lot of high desert and several secondary highways in the area...Enjoy!

I want to hear a lot more about your XR650R, Matt!

Moses 

 

Edited November 7, 2015 by Moses Ludel

[DarrenG]

Hi

Im repairing the ignition on my 1987 XL600R. Replaced pulse generator and now have an issue with kickstart feeling jammed at times. I got it running and starting much better than before but had an oil leak that required removing the cover a few more times to fix. I want to know the proper way to disengage or remove the auto decompression. I've learned alot already from your posts. Thank you

Darren

[Moses Ludel]

Hi, DarrenG...The Auto-Decompressor is part of the camshaft assembly on the XR650R.  The fix was easy for my XR650R:  I replaced the camshaft with a Hot Cams Stage 1 camshaft, which eliminated the Auto-Decompressor.

XRs Only offers a Hot Cams Stage 1 camshaft for the 1988-up XR600R and XR650L (air cooled).  Give them a call or email and ask if there is a Stage 1 camshaft that fits your 1987 XL600R and whether it eliminates the auto-decompressor mechanism.  I believe your auto-decompressor may be like my 1984 Honda XR350R and XR500R with a cable actuated release lever and arm.  My guess is that this XR600R camshaft will not work, as the lobe spacing is different between this cylinder head and your 1987 XL600R cylinder head. 

Do you have a cable release that works from the kickstart mechanism to the side of the cylinder head?  XRs Only may have a solution for the earlier style cable release decompressor.  On that note, before making changes, try adjusting the auto-decompressor cable to factory specs.  Inspect the system carefully from the cable to the lever arm and rocker release mechanism inside the head cover...You might find a problem and solution that alleviates the troubles.  My XR350R and XR500R have never been difficult to kick and have never "jammed up".  The kick starter mechanism is more fidgety. 

https://www.xrsonly.com/hot-cams-stage-1-cam-honda-xr600r-1988-up-xr650l

For the XR650R, I am very pleased with the profile of the Stage 1 camshaft.  It's not "wild" or pipe-y, idle is only affected slightly, requiring an idle speed setting at the higher end of the factory specification, otherwise no issues.  I have crawled single-track trails like El Dorado Canyon with no issue, relying upon tip-in throttle stability.  You do need to increase the carburetor jetting slightly to compensate for the camshaft's increased lift and duration.  XRs Only should have comments about that requirement if a camshaft for your 1987 XL600R single is available.

Let us know if Hot Cams makes a Stage 1 camshaft for your XL600R engine and whether that camshaft eliminates auto-decompression.  You may not be able to eliminate auto-decompression with a camshaft change.  However, there may be another route related to the cable system. 

Basic starting procedure:  If you're able to eliminate the auto-decompressor, make sure the piston is slightly past TDC before kicking through.  Using the kick start pedal, learn to edge the piston up to TDC by feathering the manual compression release lever.  Pull the lever in just enough to still feel the compression but allow the piston to rise without a lot of resistance.  Push the kick start pedal slightly past the piston's TDC on its compression stroke.  Release the compression release lever and kick down firmly on the kick start pedal.  There should be no kick back if the piston is slightly past TDC and you kick through firmly.

Moses

[DavidEasum]

Here we go - talking about that auto-decompressor again!

After several years and many kilometers of faithful service since the last top-end re-do on my XR650R, there is a noise developing in the motor (actually, it's been there for about a year, so I really need to do something about it now). It comes on randomly at low RPM - sounds a bit like a strong rapping on the cylinder head. But it's not always there. What it really sounds like is an "on-steroids" version of the click you get from the auto-decomp when the engine turns over slowly on the kick-starter. 

But I wasn't quite sure of the cause. So started with the most typical (and easy to deal with) culprits. That means I replaced the tensioner, the rear camchain slider rail and the little spring-loaded pin that goes in the head under the decomp mechanism. I checked the cam, put it all back together, set the valves and hoped for the best. Unfortunately, this did not do the trick. The thing still runs great, but the tick is still there.

While the cam was out, I did look at the auto-decomp mechanism. It didn't feel like a slick Honda part, but then again, I don't know what it's supposed to feel like. On the other hand, the anti-kickback one-way clutch (or whatever it's called) part of it seemed to be in tip-top shape. Whatever the case, I did not take it apart - for four reasons:

1. I don't have easy access to a press to put the decompressor back together on the shaft once it's apart;

2. I was hoping that the tensioner and slider rail would do the trick;

3. The part on the shaft related to the decompressor that looks like it might be the wear item is not available without ordering a whole new camshaft assembly (no part number listed). 

4. The decompressor seems to work just fine despite the noise.

So after doing a little more research, I found this video which looks and sounds exactly like mine did. 

 

 

One of the commenters said the thing is shot - but no idea if one can trust a YouTube comment on what could end up being a $400+ job.  So.... What to do? Pretty sure my next step is to pull the cam again, remove all the parts from the decompressor, put the now "naked" cam back in the head and just leave it at that. This is assuming that the noise is gone!! The cam is still good and I'm happy with the performance as-is.

The only thing I don't know about is which hole in the head I need to plug in order to maintain oil pressure when the decompressor parts have been removed. And furthermore, what to I plug it with?

It'll maybe take me a little while since I'm nursing a broken rib or two sustained in a fall on my new R1200GS. Got into some mud, slid a bit but then the undercarriage hit a big rock that bounced the bike completely sideways and promptly highsided me.

More to come....

[DavidEasum]

Forgot to mention - if you're replacing the rear cam slider rail, be careful of the M6x25 bolt holding it in place (it threads into right-side engine case - you access after removing the two right side engine/clutch covers). Mine was put in with hard thread sealer (I didn't know this and it doesn't say anything in the shop manual about it). So in removal, I managed to break it. That meant I had to remove the clutch basket to get drill access. Then I of course proceeded to break the easy-out in the hole. Grrrr...  (I know better than to do that!!). What a nightmare. The rest of the bolt and the broken off easy-out eventually came out and I put in an insert so all is good now - but don't make the same mistake!

[Moses Ludel]

David...Here's my take on the Honda XR650R Auto-Decompressor issue...As I shared earlier, I am a fan of eliminating the Auto-Decompressor altogether.  The Hot Cams Stage 1 camshaft is mild and not a quirky power curve.  The engine starts with ease when tuned to specification.  This camshaft, which I have tested in slow going terrain like Eldorado Canyon and open desert or highways, is a good pick.  (See the Eldorado Canyon video above as one example.)  XRs Only compares this camshaft's profile to the Honda HRC grind.

Here is a link to the XRs Only details on the XR650R Hot Cams Stage 1 camshaft:  https://www.xrsonly.com/hot-cams-stage-1-cam-honda-xr650r

At $280, you get rid of the Auto-Decompressor, resolve any mysteries around engine oiling passageways, and have a "bolt-on" fix.  You will now depend on the XR650R's manual compression release to find TDC on the compression stroke and take the piston slightly over the top before pushing downward on the kickstart pedal to start the engine.  Once you can "feel" the piston's position, you can kick through firmly without risk of pedal kick-back injuries.  When cold, I will pull the compression release lever in all the way and kick through a couple times to enrich the cylinder with fuel before starting.

I have seen the original "Dust to Glory" movie at least a half-dozen times just to watch the XR650Rs.  In this legacy cult film, the pit starts for these bikes take far longer than I have ever needed to start my engine.  Even flooded, I can pull in the manual compression release fully to kick through briskly several times and clear the cylinder.  (Holding the throttle wide open in the process usually helps.)  Then I let the manual release lever out just enough to feel compression.  Pedaling up very slowly to the peak of the compression stroke, I bring the piston just slightly past TDC.  Here, you can start the engine readily with a single, deliberate downward kick. 

Recap of the basic starting procedure using the manual compression release lever (auto-decompressor eliminated):  If you eliminate the auto-decompressor, make sure the piston is slightly past TDC before kicking through.  Using the kick start pedal, learn to edge the piston up to TDC by feathering the manual compression release lever.  Pull the lever in just enough to still feel the compression but allow the piston to rise without a lot of resistance.  Push the kick start pedal slightly past the piston's TDC on its compression stroke.  Release the compression release lever and kick down firmly on the kick start pedal.  There should be no kick back if the piston is slightly past TDC and you kick through firmly.

A bad day is the need to perform this procedure twice, a two-kick start.  Flooded?  Maybe three kicks, two for clearing fuel and the spark plug with the manual compression release lever pulled all the way in.  The third kick, using a normal start procedure, will usually fire the engine.

Unless the plug is unable to fire, the engine will start every time without the need to overfill the cylinder with gasoline or "loading it up" with a quantity of fuel that can cause a major backfire.  These engines, properly tuned, will start on one to two kicks.  I do this even after the bike has set for months.  With the compression release lever pulled in all the way, I will kick through a few times with the choke on to enrich the cylinder before performing a kick start procedure.

A caveat is that the manual compression release mechanism must be in top condition with a good cable.  The aim is to feather the manual lever while bringing the piston to TDC on its compression stroke—then very slightly over.  The idea is a light feathering of the manual decompressor.  You must be able to feel the piston coming up on its compression stroke; if you cannot feel compression, the release lever has been pulled in too far.

Make sure there is no wear at the rocker box/cylinder head cover and manual release shaft.  Make sure that the shaft seal is in good shape.  I seldom use the manual release for compression braking in my style of riding.  The amount of use for starting the engine should have a negligible impact on the lifespan of the manual compression release mechanism.

One reason some would prefer the auto-decompressor is lack of familiarity with how to start a high compression thumper with the manual compression release mechanism.  With relatively little practice, this manual method can be mastered.  (You cannot practice this technique with the auto-decompressor in place!)  Fortunately, I had the 1969 BSA 441 Victor Special to teach me the intricacies of starting a high compression thumper without an "auto" decompressor.  We used the manual compression release lever while kick starting these models.  This was the factory method, used with the choke either on or off in response to whether the engine was warmed or not.  If the piston was not slightly past TDC on its compression stroke before kicking through, the rider could expect a severe ankle jolt or vaulting over the handlebars.

Otherwise,  as you note, there is the expense of a new Honda camshaft with auto-decompressor.  Here's one Honda parts source that I quickly found with a price at $270 (USD) plus freight:  https://www.hondasportpartswarehouse.com/oemparts/a/hon/5053e96df870021c54be372b/camshaft-valve

Either camshaft (stock Honda with Auto-Decompressor or the Hot Cams Stage 1 Kit) would be a solution.  You would have a new camshaft with fresh lobes, etc.  This doesn't sound bad if there is any wear on the OEM camshaft.  The choice comes down to your comfort level and confidence with the OEM Auto-Decompressor mechanism.

I have the original camshaft and Auto-Decompressor from my engine.  (For reasons unfathomable to my wife of 46 years, I store stuff like this.)  The unit has relatively low hours on it and would be representative of a mechanism in "operable condition".  Frankly, I wasn't convinced of this mechanism's reliability.  The kickstart pedal's kickback seemed inherent to the design.  This put me on the path to the Hot Cams Stage 1 Kit...We can compare our Auto-Decompressor units if that is helpful.

Moses

[DavidEasum]

Hi Moses,

Thanks for your always thorough and detailed explanation! If you wanted to make your wife happy by letting go of the old stock cam from your XRR, just let me know! I may be in the US in early November so I could pick it up if shipped to VT or NJ. Think about it 😉

Having the original avoids me having to figure out how to close the oil passage - and I am not at all unhappy with the performace (except for that I'm having to replace it...)

David

 

[Moses Ludel]

David...Let's compare our camshafts and see whether my OEM camshaft with Auto-Decompressor is actually reliable and "better" than yours.  I'm confident that the cam lobes have no significant wear. 

You may recall that I had to rebuild the top end of my engine prior to ever starting it or riding.  Despite the low hours/mileage accrued by the previous owner, the poor seal on his aftermarket air cleaner had caused valve and ring damage.  I bought the bike speculating that it simply needed tuning, as it would not start.  The price was reasonable, and I took a chance based on the low hours.

I attempted to kick the engine over with the original camshaft and auto-decompressor prior to running a cylinder leakdown test, the test results leading to an immediate teardown.  The kick start balking and lack of smoothness of the kick start mechanism (prior to the engine teardown) was disconcerting.  This prompted me to build the top end with a new Hot Cams Stage 1 camshaft and to eliminate the auto-decompressor.

Parting with the camshaft/Auto-Decompressor would not break my heart.  However, I would first want to make sure the decompressor mechanism actually functions properly.  I'll take a closer look at my camshaft and the decompressor.  We can go from there.

Moses 

[DavidEasum]

Hi Moses, That's fine. I'm standing by for your feedback. Like I said, I'm in the US in late October-early November so we've got time.

[DavidEasum]

I was just thinking - To take the decompressor and anti-kickback mechanism apart you need a puller to get it off the shaft and a press to put it back on. If you really feel like doing all of that, you could check for wear on the locator pin / dowel that is mounted in the shaft itself - as well as inspect the slot in the decompressor cam to which the pin marries.

Since this pin is not replaceable I think that's why Honda doesn't list a part number for the decompressor cam that mates to the pin. If they did, people would risk replacing a worn decompressor cam without any concern for wear on the pin - thereby making for a high wear/early failure scenario - which in the end would besmirch Honda's rep for reliability. Sort of like re-sleeving an engine without bothering to replace rings and piston.

Other than pulling the assembly from the shaft, I don't think there's an easy way to be sure about the auto-decompressor short of installing it in an engine and living with it.

See the images below to get an idea of what I mean. That said, I didn't see what it looks like when it's in pieces on the bench, so take what I say with a large grain of salt. 

Personally, I'm willing to take the chance that your cam assembly is good. The auto-decomp is afterall not something that's known as a glaring weakness on the XRR - and cam removal/reinstallation is only an afternoon's work.

[Moses Ludel]

David...I will take a close look at the assembled unit.  If necessary, I'll take the cam/decompressor apart, using the factory workshop manual and correct tools to prevent damaging parts.  Expect an update with my findings...

Moses

[DavidEasum]

A job to do when there's nothing else pressing... (no pun intended). 😉

[Moses Ludel]

DavidEasum...I took a close look at the OEM camshaft from the XR650R engine.  I did not disassemble the camshaft and auto-decompressor...Below are photos.  The lobes are fine, an OHC engine with rocker arm followers seldom creates a wear pattern issue unless there is notable wear or the top end has been run without adequate lubrication.

I took close-ups of the "pin" you have described...There is side play on the adjacent plate that indexes with the pin;  the notch in that plate is still square.  The cam-ramp for the decompression mechanism does show some wear (a flat area at the start point).  The one-way clutch (a roller sprag design) seems functional and operates smoothly. 

Here are the photos with my comments:

This is the pin-and-notch.  The pin's head is rounded (dome shaped) and not square.  I'm not clear whether this is the kind of wear you describe.  Normally, a locating pin is square-shouldered.  Is this wear a concern?

 

Here you can see the pin's head clearly, and it is round or domed.  The camshaft lobes and one-way clutch seem okay.  There is some lateral movement of the plate with the notch for the pin.  This plate can be "wiggled" like the one in the video you shared, maybe not as dramatically.

The plate's ramp point has a flat area.  This may be normal for the mechanism, your video shows a similar flat.  Does your camshaft have this, too?

 

This is another view of the decompressor cam's flat.  Is that an issue or designed into the plate?  During the time I tried to kick start the engine (prior to teardown;  recall, it never started before the top end build), there was a grabby, notchy feel to the kick start mechanism.  It felt like the mechanism was jamming up...What does your auto-decompressor feel like when kick starting?  This one never felt consistently smooth or predictable when engaging.  That was my reason for installing the new HotCams Stage 1 camshaft and eliminating the auto-decompressor system.

The camshaft lobes and other areas look okay.  My concerns would be lateral movement of the decompressor cams and the rounded head of the locating pin.  What is "normal"?  Are all of the locating pins dome headed?  Is there an acceptable amount of decompressor cam movement laterally?  Do all decompressor cams wiggle?  The roller clutch mechanism seems okay, without perceptible rocking, just minor lateral movement.  Your manual's text does not note the acceptable play or norms.

How does your camshaft look and compare?  Do you have photos to share?  Is my camshaft "better" and capable of providing reliable service?  

This was a relatively low hours engine when I removed/replaced this camshaft.  The camshaft with auto-decompressor is just as it came out of the engine...These auto-decompressor mechanisms are subject to a lot of force, and there's potential for abuse.  Abuse could explain the "jamming up" that I experienced while trying to kick crank this engine.  (The resistance was not from compression at the time.)   I chose not to reinstall this camshaft and auto-decompressor.

Your thoughts?

Moses

 

[DavidEasum]

Hi Moses,

Your cam looks just like mine - but mine's got a ton more mileage on it. 😉 I wish I had taken photos of mine when it was out. We'd then have a better comparison. But it's all back together now and for that matter, I'm in France and the bike is in Burundi.

Whatever the case, the pin that you're looking at is not the pin I'm talking about. If you look at the third image of the first page of the manual that I attached in my previous message above, you'll see where I've written "PIN." Unless it's a bad drawing, it looks to me like there's a dowel sticking out of the shaft on a perpendicular axis. Since neither you nor I have taken our cams apart I guess I can't be sure if I'm right, but I think this is a fixed locator pin/dowel that fits into a notch in the decompressor cam and keeps it from turning. I believe this (and the notch in the decompressor cam) is the wear point. Like I said before, there's no part number for this pin and none for the decompressor cam either - hence, not replaceable. 

From recollection, my decompressor had a "flat" on it like yours where it runs up against one of the followers. I don't recall any particular wear marks.

For what it's worth, the pin that you mention (called "stopper pin" in the drawing above) is replaceable. It looks exactly like mine with a rounded top. There are actually some other pins - more like rollers - that fit into the one-way anti kick-back clutch (like 3 or 4 of them). Like the dowel I'm concerned about, they are not visible unless you take everything apart. On the other hand, they are replaceable.

I'm still on schedule to be in the US - as of the 24th of October for about 3 weeks.

David

[Moses Ludel]

DavidEasum...Ah, I get it, your reason for suggesting that I remove the cam sprocket drive flange and auto-decompressor for closer inspection.  In assembled form, I confirmed that the one-way sprag or roller clutch does work properly.  The concern you have is this pin, which is totally obscure and not a cutaway in the factory manual illustration.  The pin (seen below) is intact in my assembled OEM camshaft:

I poked around the internet and found the best prices on a new HotCams Stage 1 camshaft.  This eliminates the auto-decompressor.  A seller at Springfield, Oregon* has a new camshaft for $197 plus state tax, shipping is free.  If this sounds appealing, contact the seller and confirm that this is an "in the box kit" for an XR650R.  My Stage 1 camshaft bolted right in, no modifications or lubrication concerns after removing the plunger and spring.

*If you prefer Amazon and have a Prime account, they have this HotCams Stage 1 camshaft kit at $218 with free freight plus tax:

https://www.amazon.com/Hot-Cams-Camshaft-XR650R-2000-2007/dp/B07CZT979N

You expressed concerns about lubrication when owners attempt to remove the auto-decompressor from the stock camshaft.  The HotCams instructions have you removing the plunger and spring from the cylinder head when installing the HotCams Stage 1 camshaft.  You do not replace the plunger and spring, and the new HotCams camshaft is designed to operate without this plunger and spring in place.  Oiling works flawlessly, no loss of pressure or any other concerns. 

Note that you cannot remove the plunger, spring and auto-decompressor pieces when running the stock camshaft.  When owners make this mistake, they get into lubrication issues.  The HotCams Stage 1 is machined to oil properly without the plunger and spring in place:

HotCams instructions:  "Do not remove the gear holder from this camshaft as it does not use the decompression mechanism.  Also remove the plunger and spring from the cylinder head."  

Here is a photo of the plunger, spring and retainer clip referenced in the HotCams instructions.  I removed this when installing the HotCams Stage 1 camshaft in my XR650R engine.  These parts are not used with the HotCams camshaft.  The OEM auto-decompression mechanism is not installed, either.  The HotCams P/N 1009-1 camshaft comes with a timing sprocket drive flange in place.  The HotCams camshaft is installed with its timing sprocket drive flange, which eliminates the OEM auto-decompressor:

Below is a photo of the HotCams 'Stage 1' 1009-1 camshaft for the XR650R.  (This seller at eBay wants $180 + $10 shipping plus tax for the camshaft:  https://www.ebay.com/itm/Honda-XR650R-Camshaft-/284961281986.) Note that the timing sprocket flange is in place and should not be removed.  The OEM auto-decompressor does not work with this camshaft.  You use the manual decompressor lever (compression release) at the handlebar to bring the piston over TDC on the compression stroke when crank starting:

Without harping or seeming redundant, here is a quick and current (just this week) anecdote about the HotCams Stage 1...I had a Pulstar spark plug in the XR650R engine.  After some use, it simply stopped firing adequately (light orange rather than sharp blue spark across the gap).  My XR650R with Acerbis tank requires a major effort to access the spark plug, but once the tank was off, I changed the plug to an NGK BKR7EIX-11 iridium type.  (This is worth the triple cost over the standard NGK BKR7E-11, insurance against needing to remove the fuel tank to access the spark plug in remote backcountry!).  With old gas (Sea Foam in it for storage), after a two year hiatus, the engine started on the first ignition-on kick. 

This was the procedure leading up to the kick through start:  1)  pull in the manual compression release lever and kick through 2-3 times with the choke on and ignition off, 2) choke on, finger off the manual compression release lever, bring the kick start lever to full compression pressure at my heel, 3) pull in the manual release lever slightly and press down the kickstart lever lightly to bring the piston just over TDC (a slight movement, easily felt) and 4) ignition on, choke on, finger off the compression release lever, kick the starter lever down firmly.  I can repeat this process in seconds on a restart with or without the choke on.

Moses

[Moses Ludel]

DavidEasum...When you've had time to process the info above, a quick question:  Your bike was Euro spec, right?  No "D"-shaped fuel restrictor in the intake, a non-restrictive exhaust and essentially "uncorked"?  If you want to know the tune specs typically run with my Stage 1 camshaft, see coverage at:  

I'm currently running a 172 main jet that works all around.  Most of my riding is at 4,000-4,500 feet elevation, and I could drop to a 165 or 168 main for this altitude.  However, that would mean a slightly lean burn at sea level.  With the HotCams Stage 1 camshaft, the engine is flexible enough to "tolerate" this slightly enriched mix.  The OEM main jet is 175 on factory models for Europe or Australia.

Moses

[DavidEasum]

Hi Moses,

Indeed, mine is global spec. No restriction in the carb manifold and the pieces removed from the airbox. The exhaust tip is the fatter one and it makes a good healthy roar. Right now I think I've got a 172 main in it. I did have a 175 when I was living in Nigeria (sea level), but back to Burundi I've leaned it out a bit for the altitude.

It's not the easiest bike to start, but like you, I usually start it with one kick given the right procedure. If someone else rides it though I usually have to start it for them. 😉 Hot start is achieved with a little throttle - or not.

David

[Moses Ludel]

Gotcha, David...The profile is much like my XR650R...I'm running the stock-type air filter, as the leaky aftermarket type that came with the preowned cycle had caused upper cylinder/valve damage.  I'm running a new/stock Honda filter with an OEM fire screen.  The engine probably could use more air, especially at altitude, but I have never experienced a "starvation" or overly rich issue.  A primary aim is to protect the engine.

Message me about your OEM camshaft with decompressor plans.  As we've discussed here, you have options.  

Moses