YX150 knock

[vootele]

Hello all
I have strange problem, which I've been struggling for some time now.
The engine is YX150 but with KLX110 cylinder, piston and head. I got it from some pitbike racing team, they told me KLX110 parts were for reliability.
A year later maybe the engine developed ringing knock, which sounds like piston related for me. Hotter the engine goes, louder goes the knock.
In this autumn I took it apart and found nothing suspicious. No play on conrod or wrist pin, nothing banging together... Perfectly normal engine. Maybe a bit worn wristpin, which I replaced. After putting it back together, the knock is still there.
Video here:
https://goo.gl/photos/kLU9ut3BWBJ9C6F58

[Pitbikeowner101]

Originally Posted by vootele

Hello all
I have strange problem, which I've been struggling for some time now.
The engine is YX150 but with KLX110 cylinder, piston and head. I got it from some pitbike racing team, they told me KLX110 parts were for reliability.
A year later maybe the engine developed ringing knock, which sounds like piston related for me. Hotter the engine goes, louder goes the knock.
In this autumn I took it apart and found nothing suspicious. No play on conrod or wrist pin, nothing banging together... Perfectly normal engine. Maybe a bit worn wristpin, which I replaced. After putting it back together, the knock is still there.
Video here:
https://goo.gl/photos/kLU9ut3BWBJ9C6F58

Hi mate i would check your timing and clearences line t on fly wheel 12 o clock and make sure cam cog mark is at 9 o clock then i would check your clearences remove intake tappet cover(the one at the top of the engine) and remove the plug and turn the fly wheel by hand till you see the intake valve go down and come back up the T should be more or less lined up with timing marks then set the clearence 4 thiu intake and 6 thou exhaust

Wore comes to worst check your crank as conrod bairing could have gone causing piston slap

[jal123ddd]

My sons old engine was like this after some time of riding ,found out that it was the cam chain it was a little lose and reset timing and replaced the rubber head can chain tensioner rod and all fine