I'm elbow deep in a motor rebuild, and I've run across something (I thought) rather strange. You can find some pictures in this imgur album, which show one of the 4 burnished spots on the rotor. At least when I have the magneto cover removed (and the starter idler is only being supported on one end), the gap between the gear and the rotor goes to zero and they grind against each-other.
I entertained the thought that the high spots are machined to give a small amount of clearance, and slop introduced to the idler shaft by removing the support on one end caused it to start rubbing, but the spots look burnished, so I think it's been rubbing while the motor was running.
If I was confident that it was only a manufacturing defect I would just file down the high spots. However, I am not that confident. Is anyone aware of what might cause this, that should be looked into further?
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