lobe wear

3 replies to this topic
  • eductor

Posted August 25, 2004 - 01:22 PM


on top of my camlobes there is color change (grey fields).
It looks worn. see pictures
Is this normal?
The bike has run for 20hours since new
My dealer says that all thumper engine cams look like this after 20hours normal riding.

Posted Image

  • Indy_WR450

Posted August 25, 2004 - 01:55 PM


They should wear in fine as the valves tighten up. That is the back side of the cam lobe and there is very little contact pressure from the springs at that point in the timing. I cant remember what mine looked like new. But worn they will be shiny on all the contact surfaces on the lobes.

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  • WR_Dave

Posted August 25, 2004 - 03:45 PM


The valve bucket is machined with a slight concave on the face of it and the cam is designed to turn the valve slightly every time it opens , so the valves don't wear in one spot all the time. Your cam lobe looks perfectly fine. If you get very even wear across the entire lobe then I would start measuring clearances more closely. Good Riding--WR Dave. :thumbsup:


Posted August 25, 2004 - 05:01 PM


I have to disagree here. Maybe it's just the photo but those gray discolored spots look like where the hard facing on the cam has been compromised. It is fairly common on automotive engine cams that are not run in correctly (i.e. -no assembly lube used, inadequate lubrication at startup, etc). None of my 4xx's have ever had a wear pattern like that. If it were my bike I'd be very concerned. Sorry but that's my .02


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