On my 1995 yamaha timberwolf when i am accelerating I can hear a pinging noise. It is a lot more noticeable when the engine is under a heavier load. Definitely the sound of metal on metal hitting somewhere. What should I look for? I read in my manual that using a higher octane fuel could solve the problem but it didn't change anything. Only thing I can think of is maybe the timing chain is tapping against the case?

I will add that I checked the valve clearances and they are good.

 

Anyone? It doesn't smoke or anything so I don't think it is piston slap. I'm trying to sell this quad but I want to resolve this issue first.

 

I have heard this before in Yamaha's and passed it off as a trade mark noise
related to their engine design.
Maybe the piston skirt is worn out of round.
Never seemed to affect them any as far as performance goes.
I had a Kawi that had a well worn out auto clutch that made quite the noise.
Is the noise in the top end or bottom?
Hopefully a Yamaha "wrench" will chime in with some hints.
I grew up with dirt bikes in the "70's",
and a lot of the big bore single cylinder 2 strokers pinged big time,
so from the factory small rubber buttons were installed in between the cooling fins to dampen this noise.