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Discussion Starter · #1 · (Edited)
so I just bought this bike and it didnt run when i got it. cleaned the carbs cleaned the tank and now i am trying to run it on a aux tank i made and tune the carbs. when i started it, it seemed ok needed some fine adjustment. so i did the valve adjustments all into spec, started it and reved it a few times and it sounded like it back fired and reversed the motor for a second. now it sounds like i have a bent valve and sticks on revs. heres a vid of what it sounds like and does. if its a bent valve ill just sell the thing.

http://youtu.be/SsQPXpn8ZBM


After idling like the previous video i decided to throw the tank on and see what happens. ran decent enough without the carbs synced but as i was riding it started to sound like this

http://youtu.be/X76XfcKihyE

seriously annoying
 

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Could be a bent valve I suppose. If the chain tensioner did not reset itself right and it jumped a tooth of timing then it could have bent a valve:dunno. Or could be one of the shims or rockers is out of place, again, hard to tell. I would say you're just going to need to go back in and find the loose valve, check that everything is in place and that the cams are still timed right and then do a compression check. I would say you could do a compression check first, but if there is a problem with cam timing or valve clearance that is going to give you a bad reading on compression.

If you find a valve that you can not get back into spec with regular sized shims, that would be a good indication that it was bent.

Good luck and let us know how it turns out.
 

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I forgot to mention the compression test

cylinder 1- 134 psi
cylinder 2- 120 psi
cylinder 3- 125 psi
cylinder 4- 120 psi
Those all sound low. Not to insult your intelligence, but did you have the throttle wide open when you tested. If not that will cause a low reading
If you did have he throttle open when you tested, then the most likely reason for the compression being that low woul be one or both of the cams off by a tooth:dunno
 

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One other little tip I might suggest, if you did not already know. After you get the chain back on in the right position and the tensioner back in place, turn the engine over slowly by hand until the tensioner can take up all the slack. May take several revolutions and you want to be sure the chain is tighened up.
 

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Discussion Starter · #7 ·
alright so i got everything off and i rechecked all the valves to make sure they were still in spec. so i started looking at the camchain. Am i correct in assuming when at tdc and the in /ex on the cams are facing away from each other there should be 41 posts in the link (two per link, and half of one)? and here is a picture of the cam sprokets facing each other at the tdc mark.


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I assume they are not lining up because the cam chain tensioner. I snapped a quick vid showing how loose it is when i lighty press down on it.

http://youtu.be/o1_7L-JNa7A
 

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Discussion Starter · #8 ·
After tearing it all down took the tentioner out cleaned it and it still compresses about 1.5 inches against the chain so now I'm back to thinking its in the head. I guess my next course of action would be to take the came out and check my lifters? And valves?
 

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Discussion Starter · #9 ·
UPDATE**

I tore the motor all down to the lower case with the clutch and everything in it and found that my noise was a spun bushing on piston 2. which if you notice had the lowest compresson. As far as the compression being low, there was a shit ton of carbon built up on the piston heads and valves on the bottom of the head.
 
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