Cam Shafts and Buckets

3 replies to this topic

Posted July 17, 2009 - 04:30 PM


So I put a new timing chain on my bike last weekend. While I was in there I noticed that all of the buckets had a circular pattern worn into them, not very deep maybe .002"-.005" deep. I also noticed that the cam journals where they ride in head had some of the "shinny" finish removed from them, but they weren't scored or pitted or anything of that nature. A few local guys say this is normal wear and tear on a motor, I just wanted to get the real skinny on if I need to worry about the wear I am seeing. What do you think??? Bike still runs great, but I am suppose to go to the dunes next weekend and don't want any problems.:worthy: :banana:

  • grayracer513

Posted July 17, 2009 - 06:44 PM


The circular pattern is normal, but .005" is getting into excess wear.

Wear patterns on a flat tappet cam should show smooth wear in the center of the lobe, not quite out to the edge, getting wider as it approaches the lobe peak, and running all the way across the lobe at the peak. The surface at the nose of the cam must be parallel to the axis of the shaft, and not in any way "rounded" side to side. No galling or scratches should be present.

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Posted July 17, 2009 - 09:27 PM


Gray many thanks for the quick response, what about the portion of the cam that rides in the in head and is clamped by the cam caps? I thought these were called the journals, but it looks like I need to learn what I am talking about. The lobes on my cams look good according to your guidelines.

  • grayracer513

Posted July 18, 2009 - 07:29 AM


The areas you are referring to would correctly be called journals, yes. They should be free of galling, scratches, or significant wear, as should the saddles in the head, and the cam caps.

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