Intake cam hard to turn?

5 replies to this topic
  • twomancrew

Posted March 19, 2011 - 11:02 AM


YZ 450 08. Intake cam cannot turn by hand. Can move w/ screw driver placed in gear teeth. Tensioner is released. Exhaust cam moves easily. Cam journal has minimal marks, does not look burnt or discolored. Thought cam would get looser with use not tighter. Fear jumping cam chain. Need to sell bike and do not want to just pass on problem. 7ftlb torque. Bike has a ton of hours on it.

  • tech24

Posted March 19, 2011 - 02:12 PM


I assume you had the cams off???? Remove the cam again. Make sure the cam journals are very clean and apply plenty of oil then toruque down in stages to 7lbs for example torque them in a criss cross patter to 2 ft lbs then repeat to 4 ft lbs the to 7. I have had this problem before as well, hopefully thats all it is. I've even had a 250f that Were stiff when done and nothing I did made it any better. Fired the bike up and let it run and rechecked. They were free to spin again.

  • RJacks

Posted March 19, 2011 - 02:13 PM


What about your clearances? Are they tight?

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  • Padgett

Posted March 19, 2011 - 06:53 PM


Did you forget to put the half moon key in the cam bearing?

  • twomancrew

Posted March 19, 2011 - 07:06 PM


Actually took this cam journal off to steal the half moon key for another bike. Got new key. Did not check valve clearances. Will check clearances. Had not thought that if a clearance is tight it would restrict movement. Just ordered new inch/lb torque wrench. When I get it I will tighten in stages also. Thanks for the fresh perspective and input guys.

  • grayracer513

Posted March 19, 2011 - 07:13 PM


He's talking about checking the clearance between the camshaft and the head (or at least he should be). This is done with a "PlastiGage" as shown in the manual.

The intake cams tend to be fitted quite snugly in most YZF's, and it is fairly normal to find them feeling tight to rotate with the fingers, but they should not be impossible. Is there a chance you torqued the cams incorrectly (not in sequence, and/or without a torque wrench)? The caps are very easily distorted.

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