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We opened the engine today to do some maintenance and we found the end of the camshaft was damaged, we already have a new one in order but we would like to hear your opinions on why this would happen. Remember this is a modified camshaft so one possibility is that it was weakened during the process

Here are the pics

Camshaft 1

Camshaft 2


  • 1
    Could be vibrational force I suppose... Or centrifugal force... It'd almost have to be from bad piece of metal. Commented Jul 14, 2016 at 15:00
  • 1
    Yeah. I mean the RPMs do rev pretty at times, and generally the quality of the parts (OE) are as cheap as can be. But since this was an aftermarket/performance part... It's odd. Commented Jul 14, 2016 at 15:07
  • Is that even part of the camshaft? Looks like part of the bearing cap has chipped off
    – Zaid
    Commented Jul 14, 2016 at 21:04
  • Hi, yes it is a part of it although it doesn't seem to have any function at all
    – Aerim
    Commented Jul 15, 2016 at 18:02

2 Answers 2


It is stress, vibration. Shouldn't happen like this, but if it is reground cam shaft, it might be dropped. Normally if you drop a cam shaft, crank, piston, valve, etc, especially on bike engines, where you have minimum of a material and maximum of a performance, you just have to replace it. It is cheaper than a new engine. My co-worker once dropped a cam shaft and it just broke in half.

  • 1
    Heat treat is a fine art, and takes a whole lot of skill. Its quite easy to do it wrong. Too hard = brittle, too soft = poor durability.
    – zipzit
    Commented Jul 14, 2016 at 18:19
  • So I was told elsewhere this is "common" and that the part is still good, what do you guys think?
    – Aerim
    Commented Jul 20, 2016 at 14:03

This guide flange is a delicate part of the cam. The damage shown is caused by improper disassembly. If the cam caps are loosened while the cam lobes are facing down, the torque of the valve springs pushes upward unevenly causing the flange to be trapped in the valley and generally results in a hairline crack that eventually fails. A clue to the improper cam removal is the aluminum marks on the flange itself.

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