Ninja 300 camshaft failure, possible causes?

Question

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

Thanks!

score 3 · Answer 1 · answered Aug 02 '17 at 02:58

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.

score 2 · Accepted Answer · answered Jul 14 '16 at 16:33

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.

Ninja 300 camshaft failure, possible causes?

2 Answers2