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Hey guys, I believe I have some "Auto-Decompression" issues. It happened randomly and suddenly on the way home from work a week or so ago; I came to a stop sign and heard a "plop plop clack clack plop bluh" and she died. Started back up, drove around and then when I was slowing down again, "Clack clack plop plop bluhh ded" like it was mechanically failing at low rpm idle. It does not happen every single time it idles, but just often enough to stop riding it for fear of really &%$#@!ing stuff up. I didnt get a video of the clack clack plop plop upon engine failure very well but it makes the noise on start up as well. 

 

My Climer manual doesn't have info about the auto decompressor but I have heard it's an issue that sometimes happens.

http://www.partzilla.com/parts/search/Honda/Motorcycle/2008/XR650L+A/CAMSHAFT/parts.html

I think I'm looking at replacing #6, #10, and #5 on that microfiche. Can anyone confirm this is a problem that exists or do you think I have a different issue? I want to get some feedback before I start tearing into it. :)

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Put an aftermarket cam in it and get rid of the decompression crap , it's not needed. 

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50 minutes ago, JoeRC51 said:

Put an aftermarket cam in it and get rid of the decompression crap , it's not needed. 

Right on, I had heard it "wasn't needed" but my school of thought has always been "When in doubt, go stock, the engineers are smarter than you." Just want to make sure that without that decompressor the starter motor will still crank over without additional strain, and when I add a kickstart it won't kickback and break my ankles. 

So I'm probably looking at $150-200 to get a Hot Cams 1004-1. Boy oh boy do I enjoy doing top end work haha.

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The cam will bleed off compression at low RPM anyway , I've got an 11.25 piston. The cam swap is pretty straight forward. Make sure the pads on your rocker arms where they contact the cam are in good shape. Use synthetic MC oil and keep it clean.

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TxSam,

 

I have a brand new Hot Cam on the bench. $125.00 and it's yours.

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6 hours ago, mcma111 said:

TxSam,

 

I have a brand new Hot Cam on the bench. $125.00 and it's yours.

Definitely interested but I gotta do some budgeting and bill paying first. You have an address I could send an Email to? Thumper Talk says "Mcma111 is unable to receive messages" :(

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TxSam,

 

mcma111@aol.com

Edited by mcma111

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It could be it is misfiring or spitting back into the carb for some reason, and it's just stalling.

When my idle is too low or it's idling crappy when it stalls it'll act like the decomp/anti-reverse engaged.

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So I'm in the process of taking apart the cylinder head following the Haynes manual (I know, FSM or death but it's what i have.) and the Haynes book says that I should be able to remove the head cover and cylinder head without removing the engine from the frame. But in my attempts to do so, I cannot find a single way in which the cover can be removed while the engine is still in the bike... Am I going to need to drop the engine to replace my camshaft? I can do it.... i just really dont want to...

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Disconnect the ''choke'' from the carb , unbolt the heatshield   from the pipe and unbolt the rear brake reservoir from the frame.  The carb will just barely fit out the right side of the bike. Raise the rocker box up and also hold up the long bolt in the middle. Move it towards the back of the motor and it just barely fits out.

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Think I found my problem.

 

Got a new cam Hot Cam on order and will probably go ahead and do a top end rebuild while I'm waiting, lap valves and clean etc. Also going to replace some busted gaskets. I'll post another update when she's up and running again. :) Thanks for all the advice guys. 

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Does that have a paper rocker box gasket on it now ? Don't use anything but an OEM Honda gasket for the rocker box , it's laminated metal and is also a spacer for the cam.

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Alright. Got my cam in from mcma111, thanks a million by the way, and got my gaskets etc and am ready to bolt them down. But, like the super smart person I am, I rotated the engine over to clean the top of the piston and inside of the piston tube and didnt count my rotations.... so TDC is either correct or one rotation away... I also don't remember in what position i extracted my cam soooo.. it's either one of two ways. A video about installation of a hotcam said to install it with the lobes facing downward. Seems correct to me, but as always, am I doing this right? haha. Can't wait to BRAP around again, three weeks is toooo long. Also attaching some pictures from my valve job, before and after lap job. Don't worry, I replaced the valve steam seals so there won't be anymore oil fouling like there was on right side intake valve, but dang did this bike need its valves re-lapped. Previous owner ran it rooouuuggghhh. 

Exhaust valves- Left untouched, right once over with wire wheelIMG_20170723_135047790.jpg.02e555bb5204f1f660ec194294790110.jpg

Bottom of exhaust valves. Left untouched, right once over with wire wheel. (I made both of them as clean as the intakes in the final picture.)

IMG_20170723_135104310.jpg.22f4a0de283eb13b3e65f82211fbdd31.jpg

Intake - Left untouched, Right untouched (Oil fouling from leaking valve stem seal, seal has been replaced.)

IMG_20170723_140459324.jpg.5411ecd7c77cf681c27340d212406cd0.jpg

Intake- Left has been hit once with wire wheel, Right untouched, major buildup and fouling. No Bueno.

IMG_20170723_141100059.jpg.bb28ecff3e851e0ad5558730f2d9c431.jpg

Intake final result. Didnt get a side view, but both intake and exhaust now look semi-new.

IMG_20170723_142746528.jpg.fd9a9b2bb30fcaccd2f90aaa914cbd2c.jpg

I was able to get a good dull gray band around each valve and valve seat after lapping so I didn't have to replace any valves or the top end, thank goodness. Today I put everything back together, cross my fingers and ride off into the night. Hopefully.

 

This is only my 3rd top end rebuild of any bike so I'm still fairly new, but my advice to anyone who is thinking about tackling the project is to just jump in. Buy yourself a $30 valve spring compressor from harbor freight or amazon, read up a little bit on it or have someone with experience watch over your shoulder and dig in. Make sure not to loose those valve keepers though, and a small magnet glued to a stick helps extracting and reinstalling them. Once you're done you really get a sense of pride and accomplishment that you just dont get from riding alone, plus you save yourself about a $300-600 (sometimes more) mechanic charge. Plus plus you actually KNOW that those valves were lapped and have a good seal and weren't just told "Yeah we did that, trust me." 

Anyway, enough rambling, sorry for the long post but it's my thread. :p In the future I hope to do more comprehensive posts and maybe some videos that might help some new owners or new mechanics get into their bikes with a little more confidence, or to expose really weird niche problems and have good photos and coverage about them that are hard to find online.

 

Snap, also, I forgot... When I am re-installing the cam chain tensioner, the book recommends the special Honda cam chain tool with the curve and pin, but I aint got that. Any ideas of what I could use to compress that spring and get it situated without breaking stuff or getting wildly frustrated? Thanks again guys for the patience and advice :)

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Welp. Might have had a wrong diagnosis, or maybe just didn't get EVERYTHING that was wrong with it..... Damn I love previous owners who are 5#!7 kicking rednecks and abuse their equipment... :) 

On the plus side,  the top end and the Thump have never sounded better, and on the down side is there is still a click coming from the engine and the problem of "Clack clack clack *dies*" persists. It seems to happen under load, like constant acceleration that puts a decent strain on the engine. My best guess is that something in the crankcase is dead or very near death. It seized up or felt like it for a microsecond as I tried to troubleshoot it riding up and down my street. I'm at the extent of my mechanic knowledge now and have never tackled a crankcase.... but that's where the problem lies...  

As the "Clack clack" gets louder, there seems to be more resistance on the motor turning over, the sound gets louder, the motor gets slower until it doesn't have enough momentum to get back to TDC and fire again. 

I'll try to get a decent video later today of exactly what it's doing so I can be more accurate is describing my issue. I would be amazed if someone else has had this issue as I seem to be very lucky with getting unique and quirky problems that not many have encountered. 

 

Edit:: The bike stays running longer when I have it in gear, as soon as I bring in the clutch because I notice that noise, the engine dies. I don't know if it's seizing up and binding, but it will start right back up after a few seconds of being off so it's not locking up and staying locked.

 

Edit2: Since this is not a decompression issue any more I'm going to create a new thread for engine failure.

Edited by TxSamsquanch

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