Yz426 motor noise?

5 replies to this topic
  • NorCal426JAY

Posted February 15, 2011 - 04:18 PM


Hello, I have a couple questions I was hoping someone could help me with. My 2001 yz 426 started making a pretty good clacking noise the other day. It stays consistent at all rpms. No valve problems, runs very well. Just got loud all of a sudden. Took it apart and was wondering how noticeable rod play would be.
Any other ideas would be appreciated

  • grayracer513

Posted February 15, 2011 - 09:54 PM


It depends on how much rod play there is, of course. The clearance is measured by rocking the rod side to side on the bearing (NOT sliding it back and forth) and measuring how much the top of the rod moves. The max is 2.0 mm.

You should also check the crankshaft drive gear nut.

  • NorCal426JAY

Posted February 16, 2011 - 05:52 AM


Hi, thanks for the response. I have checked the crank gear nut. I took off the clutch side cover and checked everything in there. All was nice and tight.
I am going to get a dial indicator and check the rod play. My valves were off a little, do you think that would sound similar to a clacking sound?

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  • grayracer513

Posted February 16, 2011 - 07:53 AM


If they were loose, yes, but that would be unusual. Check the condition of all three cam chain guides and the cam saddles for scoring.

  • NorCal426JAY

Posted February 16, 2011 - 11:50 AM


Stoked! It turned out to just be loose valves. Put it back together, and the noise is gone. Back to normal. Thanks for the help grayracer.

  • houndog426

Posted May 11, 2011 - 06:30 PM


how loud was it, mine is also making a noise, not sharp, just there, sounds like a DR350 any advice

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