Need help to identify this knocking noise, my client is on a tight budget and need to know what it is before i tear it down.
I thought it was piston slap but dosent knock when cold.

Engine noise

p.s.:Already replaced the timing chain cause it was rattling.


Thanks !

 

Sounds like my '04 YFM 350! I've been told that it is typical for air cooled Yamaha engines (only when hot). I've tried adjusting the valves but that didn't fix it. Makes the noise at just above idle. Also adjusted the timing chain tension... did not fix. Dealer also said that sometimes the auto clutch will rattle some. I've seen several threads on the Yamaha forum complaining of the same noise. Not pleasant, but nothing has blown up on mine yet! The dealer even warned me of this noise before I bought the machine (new).

Hope this helps

 

Has no one else heard a 350 Wolverine make this noise? [img]i/expressions/face-icon-small-confused.gif[/img]

I was hoping that someone else would validate my dealers explaination. This is supposed to be common on these motors.

 

Damn...........My Wolverine has a slight tapping noise coming from the top end (as did the Warrior I once owned, it is quite common), but no where near that loud. If I had to express it as a percentage, I would say my engine is only 10% (if that) as loud as that audio file. I'd have a tough time considering that normal, no matter who told me so...

 

I agree it is really loud; mine is too but only when hot. It's also hard to tell where it is coming from. Sometimes it sounds like the top end, sometimes it sounds like the clutch area. One of these days I'm going to pull the side cover off and examine the clutch. I don't think it is piston slap, as that should be worse when the motor is cold. I guess it still could be the valves but I haven't had any luck adjusting them so far.

I hope we hear back from Speeddoo if he ends up tearing it down and discovers what it is!

 

Definitely not piston slap nor the top end, does'nt knock under load so we can rule out the crank. I've analyse the noise with an audio editing program and was able to determine the frequency of the noise, it knocks on the power stroke (every 2 revolutions).

NorthernATVer is right its hard to tell where it is coming from, i've tried several time with an electronic sthetoscope and was unable to pin point the noise.

I'll keep you posted if i find anything. [img]i/expressions/face-icon-small-wink.gif[/img]

-Speeddoo-

 

Thanks Speeddoo. I listened to your audio file again and man that is EXACTLY how mine sounds. Good luck and please let me know if you find it!

 

Hey Speeddoo- ever find out what the noise is?

 

Unfortunatly i dont have the atv anymore but he will bring it back in spring. But i think i found something that might cause the knocking, i'll need to do some testing so i'll need the atv for that.


Balancer drive gear

 

Balancer drive gear.... interesting. Are you thinking that there is a problem with it or just that some are noisy?