Strange Compression loss..

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Hey guys thanks for all the replys. At this stage I haven't had much spare time to pull apart the motor. From memory, I beleive it's the yx 140. To pull the clutch in, it feels normal. And as for the timing, I have checked and re-adjusted the valves, I didn't notice anything out of the ordinary there...

Hope this is some help ??

Cheers
 
Hey all,

Ok, so i know this is a very old Thread of mine! (that i hadn't forgot about). However, i have finally had the chance between work and everything else to sit down and take a look at my bike and have just taken the head off it to look a little further and find what i believe to be a 'stuck open' outlet valve, after removing it i have noticed that it was bent. I was just wondering if anyone can tell me what causes the outlet valves to bend ?? i have heard/read that a bent inlet valve is caused by advance timing (if im correct) but curious as to what has caused the outlet valve to bend ? any help is greatly appreciated as always!

sorry to revive my ancient thread, just figured it was better re-posting here rather then creating a new one!

Thanks in Advance
 
Could be a faulty part, Foreign material got stuck between it and the seat, maybe oil in the chamber or some water as water and oil do not compress at times can result in a bent valve. Could have also gotten extremely hot and bent at the weakest point.
 
rotn50 said:
Could be a faulty part, Foreign material got stuck between it and the seat, maybe oil in the chamber or some water as water and oil do not compress at times can result in a bent valve. Could have also gotten extremely hot and bent at the weakest point.
Click to expand...

Hey rotn,

Thanks for the reply. Thought i should ask, as i was trying to find some info about it but could only find things about bent inlet valves, not so much the outlet etc.

Thanks for the response, always appreciated!
 
is there a chance the engine wasn't at TDC when you adjusted the valves ? with the flywheel mark at 12 o'clock and the cam mark at 9 o'clock
if so , then that may be the cause ?
 
Could also be the piston smashing into the valve if it let go.

Have you checked the piston and barrel?
 
The piston seemed fine no scars on the top whatsoever, so finally got it going. Had a bent outlet valve, and cracked valve seals. So just fitted a new head instead of fixing / stuffing around with the old head and valves. It's aliveeeee again after all these months haha
 
It seems a bit oily or smokie around the exhaust but that i will give that a good degrease tomorrow. It's beer o'clock now. Thanks for all the support and help here on the forums guys [emoji106]
 
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