Author Topic: CB750K1 - Do radial marks on crankshaft taper and alternator rotor taper matter?  (Read 696 times)

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Offline gkaraolides

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Greetings all,

I recently removed my CB750K1 alternator rotor to get at the starter freewheel, because the starter tended to spin and not turn the engine, especially when the bike was hot.

As seen in the post referenced above, removing the rotor was not easy, it was well and truly wedged fast to the crankshaft taper.  So I was really surprised to find some radial marks on the cranshaft taper where the rotor fits:



There are corresponding marks on the inside of the tapered hole in the rotor.

None of the marks are very deep at all; they don't catch my fingernail when I run it over them.

I have a couple of questions and I'd appreciate feedback from members.

1.  Should I do anything about these marks, like lap the rotor onto the crankshaft taper, before re-assembling?

2.  Since the rotor was wedged so tightly to the crankshaft (and the bolt that holds the rotor was on really tight too - I had to use my air impact wrench on it), how come these radial marks are there?  How could the rotor have spun on the crankshaft taper to leave radial marks, if it was on so tight?  The obvious answer is that the rotor may have been fitted more loosely in the past and re-fitted more tightly later on, before my ownership, but could there be a less obvious answer?

Best regards to all,

George
« Last Edit: August 10, 2010, 01:04:38 AM by gkaraolides »