Cam seized, has my gear slipped? How do I check?

1 reply to this topic
  • Brett1981

Posted February 17, 2009 - 03:04 PM


I had issues a while ago where I either overtightened cam cap or lost oil supply to the cams on my YZ426F 00'. This caused my intake cam to seize up, cam chain slipped, pistion hit valves, big head aches! I have been trying to find out if the cam gear has spun because I have read this can happen. When I get the cams set at exhaust TDC on the timing marks, the lobes are pointing in oppostie directions. Should they be pointing away at exactly the same angle from the level of the head straight line? It looks like the intake cam lobes are pointing a few degrees higher towards the sky when the timing marks are set to TDC, is this normal. I am thinking maybe when the piston hit the intake valves, it pushed the valves onto the lobes and pushed them higher up.
Does anyone have any suggestions on the best and easiest way to check if the cam gear has spun or is it ok that the lobes look in general close enough to pointing in the opposite direction? Maybe just try and start it first.

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  • grayracer513

Posted February 17, 2009 - 03:10 PM


Unless there is some very obvious deviation from the normal position, the only way to tell is to use a degree wheel and check the actual valve timing.

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