2008 Yamaha Raptor 350 making grinding noise . . . - Yamaha Raptor Forum
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post #1 of 5 (permalink) Old 09-13-2011, 11:05 AM Thread Starter
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2008 Yamaha Raptor 350 making grinding noise . . .


I have encountered an engine noise issue on my raptor. It just started within the last ride I was on two weeks ago. I am an industrial mechanic by trade. . . .so I am not at a complete loss with mechanical aptitude.I just figured I would research the issue a little before tearing into the matter.

So the noise I speak of occurs immediately at start up and while the engine is running. I can only explain the noise like ice being chopped in a blender or an ice maker in a home fridge cycling and dumping its ice in the tray.

It is rpm specific, meaning the noise follows the engine increase in rpm. The motor has had a top end tick while in 6th gear at mid to wide open throttle, yet this noise seems to be coming from the bottom end. The engine seems strong and I am not hearing a pronounced rod knock. The noise is an oscillating sound, which tells me it is related to the reciprocation of the motor.

Today, I am going to listen to the motor with my mechanics stethoscope and try to trace the root cause. It sounds pretty bad and I ended up riding it in from the trail in this condition. . . .so, I am a little leery of running it to much.

I should add, that my last ride involved a lot of mud, sand and water. . .so I am suspect of that as well. I changed the oil right before this ride and thought. . . now watch the engine go bad after the oil change!!!!!

I've seen info regarding starter or timing chain causing this noise. I have also notice that my tranny is having issues while trying to downshift and that is become more pronounced.

So I am making this post to see if anyone else has had any experiences with the engine noise I speak of?

Last edited by Need_more_throttle; 09-13-2011 at 11:12 AM. Reason: Forgot to add detail
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post #2 of 5 (permalink) Old 09-13-2011, 03:12 PM
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Location: Michigan
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I had a similar noise on my 08 and it happened to be the rod bearing. Unfortunately it didn't take long for the bearing to spin off after first hearing the noise.

As far as the top end tick, check your valve clearances. These need to be checked on a regular basis if you ride alot.
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post #3 of 5 (permalink) Old 09-13-2011, 10:22 PM Thread Starter
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Red face 2008 Yamaha Raptor making gringing noise . . . .

Thanks for the reply . . . . I drained the oil that was changed just before this last ride and found a lot of metal shavings in the oil plug from the bottom of the engine. Went into the the stator side of the motor, and inspection cover for timing chain. Chain is good and no slop, one way clutch for starter is good. Took out the plug and rotated the crank by hand back and forth and now I can hear the knock. I'm thinking rod bearing or wrist pin now. Either way, this bike is done for a while until I get the chance to go through it.

Now is the time for tear down and inspection, rather than blowing the motor. Great excuse to add performance parts

I would agree about the valve clearances. That will be covered in the rebuild, so this way I will have a bench mark to go from. I bought the bike used. . .but it's not always easy to tell how beat the bike was. This one was in great shape when I picked it up. . . .and ran strong. I'll admit. . .I beat the poor thing. I need to be on a bigger quad . . . 350 just inst near enough for me!!!

Guess it'll be the Honda TRX this weekend. . .good to have at least something to ride as a backup!!!!
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post #4 of 5 (permalink) Old 09-12-2019, 10:34 AM
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If you are hearing what I think your hearing which is a high pitch spinning sound. I had this on my 2011 raptor 250 and when I looked it up people said that it was the flywheel spinning on the chain and that it wasn't a problem. Its loud because the 250 isn't loud enough to cover the noise
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post #5 of 5 (permalink) Old 10-23-2019, 11:50 PM
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Pull off the clutch side cover, bet you'll find the clutch hub rubbing the inside of it. Take the clutch apart, you'll find the basket has been rubbing the retaining washer on the shaft, giving the assembly too much runout.
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