HELP.......she starts, she doesn't start, she starts, she doesn't start

ah, frustrated. a few weeks ago, i started a thread :

'can't start my yammie. the response was great and we were all lead to believe it was an auto decomp failure.

he is the most recent chain of events. thanks for your help again

do you know of any trends on the 06 yz450f that the auto decomp mechanism is failing. my bike never had a problem starting, then bamm, one day no start, super tough to kick the kick starter.

i did a valve adjustment, cleaned and oiled all the parts, the auto decomp on the camshaft seemed to be working fine. put the bike back together and whamm, she fired right up. fast forward, went to go riding the next day, fired up to warm it up, rolled on the throttle a few times and then killed the motor. got my goggles to go ride and bamm, the kickstarter was super difficult again and she won't start again. same repeat problem.

i'm really not certain what i fixed the during my valve adjustment? any ideas

thanks

dave 702 682 5991:banghead:

It's kinda of a stretch, but is the pin in the camshaft that come out to lift the exhaust valve sticking or binding. Maybe it's not coming out far enough to lift the valve? I am just guessing I have no experience of this problem. Good luck!

thx man, i actually think that is exactly what is wrong. off to tear it apart, again. hey it justs means i'm one step closer to getting it running again.

How's the fuel? Have you cleaned the carb?

My buddies CRF450 had similar sounding issues - even the kickstarter issues, not sure what causes that though. (he had bad fuel - excess water in gas)

Have you tried putting it in gear and rocking it back and forth? I've read about guys having the same problem you are describing (usually after stalling the motor) and this helps the pin to disengage and work.

Have you tried putting it in gear and rocking it back and forth? I've read about guys having the same problem you are describing (usually after stalling the motor) and this helps the pin to disengage and work.

Yeah, you put it in gear and roll backwards (takes the piston down)

Have you tried putting it in gear and rocking it back and forth? I've read about guys having the same problem you are describing (usually after stalling the motor) and this helps the pin to disengage and work.

Motox100 has a good point. However it sounds like you are having this way too often to be random. Perhaps grayracer will pick up on this thread. He will have some insight.

Sounds like it may be a valve out of spec....I would double check clearances again

It sounds like a "normal" situation in which the engine stalls against the compression stroke before it slowed down enough for the decompression flyweight to drop back and extend the pin, although I agree, it seems like it's happening more often than normal. The next time it does this, put it in gear and pull it back a little. If that clears it up, then that is what is happening.

The only other advice I have is to check that the decomp linkage all works smoothly and that the spring returns it positively. Put the engine at TDC to check it; the pin cannot be down against the lifter while you are inspecting the operation.

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