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Threw the right exhaust valve shim.

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So I go riding yesterday, we are out about 15 miles in the hills when I kill my bike and take a break. When I go to start it back up it acts like the battery is dead but I just dont think its the battery. I try kicking it and its close to impossible to get it to turn over. I wind up getting towed by one of those orange bikes, I sure hope no one was watching.

So today I charge the battery, it still wont turn over. I pull the valve cover and the first thing I check is the auto compression release and its not working, then I see why, no shim on that valve. I got real nervous thinking where is that shim, luckily it was sitting right in view.

How did this happen? All I can think is somehow while riding I hit the compression release lever. I really dont know, any ideas? I really cant see how that shim can come out.:applause:

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I had exactly the same problem. All I could think of is that I hit the decomp accidentally while riding. See valve photo here for what I found...

http://s47.photobucket.com/albums/f169/Kiwichipster/

It had fair mashed the spring retainer, so I had to get a new one. Replaced the retainer and dropped the shim back in and it has given me no problems ever since (touch wood!!).

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Hmmmmm...the Portuguese importer told me that many riders remove the auto-decomp cable from their bikes...don't remember if he told me that was for weight saving or not...guess i found a good reason....

Tomorrow i will remove it ASAP...i don't use the thing anyway...

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Do you know for sure that it was caused by the manual decompression?

Didn't George at Uptite say there was no way a shim could come out while the engine was running or using the manual decomp when running unless something else was wrong?

How about adjusting the free play (increasing) on the decomp cable so that the right exhaust valve is opened as little as possible to release comp?

I just checked and shimmed mine yesterday, my intakes are still spot on after getting slightly tighter in the first 40 hours, and now after 135 hours my exhausts have moved to the lower side of spec, I wet sanded them a couple of thou to get them at mid spec.

Please let us know if you find the true cause.

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did away with the manual decompression thing. the bike does have an auto setup that disengages it's self after 800 rpm.

try this next time your changing your shims. feeler gauge, dip it in oil kinda like the cam lobe.. touch the shim with the flat spot of the feeler to the shim.. might not pop out right away but at 700 rpms.. not too comforting ehhy

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Word from the Husky rep a couple years ago,was using some shims of the same diameter for other bikes with the radiused edges couls slip out. The factory shims have very sharp edges.

I've used shims from Honda F-2's and other Japanese sportbikes, as well as other dirtbikes. I do not know if this is true but for extra piece of mind always use sharp edges shims (face to edge come to a perfect 90 degrees...not that the edge is sharp),

Cheers,

William

Santa Cruz

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So I go riding yesterday, we are out about 15 miles in the hills when I kill my bike and take a break. When I go to start it back up it acts like the battery is dead but I just dont think its the battery. I try kicking it and its close to impossible to get it to turn over. I wind up getting towed by one of those orange bikes, I sure hope no one was watching.

So today I charge the battery, it still wont turn over. I pull the valve cover and the first thing I check is the auto compression release and its not working, then I see why, no shim on that valve. I got real nervous thinking where is that shim, luckily it was sitting right in view.

How did this happen? All I can think is somehow while riding I hit the compression release lever. I really dont know, any ideas? I really cant see how that shim can come out.:applause:

Very sorry to hear it. That must've been tough.

At least you found the problem and nothing is seriously broken:thumbsup: Better than that red bike I saw that threw a connecting rod through the case:eek:

I hope you get the issue resolved soon so you can enjoy your bike again:applause:

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I guess lucky for me there was no damage, I dropped the shim back in, checked the gap, spot on at .008 and fired the the bike up. It was actually a stock Husky shim so it couldnt be the shim. The bike has got over 3000 miles and this is the first problem Ive had that I dont think I created somehow. I am just going to disengage the manual compression release, I never use at and as long as the auto compression release works you really dont need it.

FWIW, you will know if this happens, E-start will not work and kicking it is close to impossible with only only 1.5 exhaust valves working, the auto de-comp works wonders.

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FWIW, I have the HotCams complete shim kit and looking to shims, they look sharp as possible...so, i guess no problems if you use HotCams shims.

I just removed the Manual decomp cable and even the plastic lever, its screw and bushing...some dozens of grams less :applause:

FWIW, several years ago when i had a KTM 620 by accident i pulled the manual decomp lever instead of the clutch...no problems but that engine

had screws and nuts to adjust valves instead of shims...just to be on the safe side, i really don't want to , by accident, pull the manual decomp lever if i go in very high RPM...i bet that it won't be good...

Word from the Husky rep a couple years ago,was using some shims of the same diameter for other bikes with the radiused edges couls slip out. The factory shims have very sharp edges.

I've used shims from Honda F-2's and other Japanese sportbikes, as well as other dirtbikes. I do not know if this is true but for extra piece of mind always use sharp edges shims (face to edge come to a perfect 90 degrees...not that the edge is sharp),

Cheers,

William

Santa Cruz

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Wooo Hooo ! so lucky no damage was done. if you still have the MIA shim no worries just open the bottom chamber with the screen filters are located stick a magnetic stick and you will find the jumping shim being the lowest point of the motor.. :applause: ..

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FWIW, you will know if this happens, E-start will not work and kicking it is close to impossible with only only 1.5 exhaust valves working, the auto de-comp works wonders.

You have described this twice and I still don't get it - The motor is physically locked up or does it spin freely?

.

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You have described this twice and I still don't get it - The motor is physically locked up or does it spin freely?

.

I'm not sure what he means but possibly the lack of the shim makes the auto decomp not to work, and so, the ES doesn't have power enough to overcome the engine compression or if does, the engine will rotate so slow that it will never fire up...the KS will also be almost impossible because it will be extremely hard to overcome compression if at all w/o the autodec working and so, even if engine rotates with the use of the KS, it will be almost impossible to fire up the engine.

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The little starter motor does not have enough power to turn over the motor without the auto decompression and when trying to kick it there is so much compression it extremely hard to get through TDC.

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Other than a valve sticking down, the only possible way for a shim to pop out is if stepping on the rev limiter it throws the valve train so out of balance that possibly could cause valve float/momentery valve bounce???When you check your valves this is the point where the rocker is at it's most clearence. Even if the decomp is pulled it pushes on the rocker to open the valve closingthe clearence. Next time adjusting the valves pull up on the decomp lever and try to put feeler gage in can't happen. These shims like to hide behind the valve springs in the corners where you can't see them have had to pull cam to find it. Later George

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Other than a valve sticking down, the only possible way for a shim to pop out is if stepping on the rev limiter it throws the valve train so out of balance that possibly could cause valve float/momentery valve bounce???When you check your valves this is the point where the rocker is at it's most clearence. Even if the decomp is pulled it pushes on the rocker to open the valve closingthe clearence. Next time adjusting the valves pull up on the decomp lever and try to put feeler gage in can't happen. These shims like to hide behind the valve springs in the corners where you can't see them have had to pull cam to find it. Later George

Thats kinda what I thought but it always seems to be the right exhaust shim on the few that have done it, it just seems that it might have something to do with either the manual decompresion or the auto because they both push on that valve...strange. With as bomber as the valves are on these bikes I kinda wish they just had the bucket over shim design.

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George,

You are right but like Sharpie1 says, its strange that it seems that its always same valve...maybe pressing the manual dec lever at very high RPM and then releasing it makes sometimes the valve kinda stick down for a fraction of second big enough to the shim pop out ?!?

Maybe it sticks because suddenly the valve is open for a relative "long time" with hot gases passing by it constantly making it "overheat" a bit to much and sticking slightly for that fraction of second ? then, the fresh gases will cool valve and valve gets free again but in the mean time the shim might pop out depending of the exact position where valve was stick.

Sharpie1,

No, i have to disagree in this one, i like that HVA uses the current system...better for valve adjustments and i have a feeling that it makes less stress in the valve stem.

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I guess lucky for me there was no damage, I dropped the shim back in, checked the gap, spot on at .008 and fired the the bike up. It was actually a stock Husky shim so it couldnt be the shim. The bike has got over 3000 miles and this is the first problem Ive had that I dont think I created somehow. I am just going to disengage the manual compression release, I never use at and as long as the auto compression release works you really dont need it.

FWIW, you will know if this happens, E-start will not work and kicking it is close to impossible with only only 1.5 exhaust valves working, the auto de-comp works wonders.

Has anyone checked their valve seat after this happens?

Could debris get between the valve and seat at closing just long enough to hesitate the valves movement thus throwing the shim up and out of position?

maybe a chunk of carbon off of the piston?

Does you bike run a little rich?

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I just removed my manual decomp. lever and cable to prevent this possibility.

Never use it anyway!

I don't know if HVA wanted it used in this manner however I use the manual decom lever like a hot start lever except I turn the motor over a couple of times to let in cool air then close it and fires up. I only do this when I stall on the track.

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