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- May 5, 2017
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Thomas,As I believe has been mentioned, one can skim the rotor to a smaller diameter to get the required clearance -- at a performance cost, however. In my BMW wrenching days we used to have alternator rotors rewound rather than replaced. The motor shop that rewound the rotors would take a skim cut at the end of the job to make sure they were true. After several customers complained the batteries would not stay up after the rewind, I investigated and found that a cut on the rotor reduced the output from 20A spec to as little as 14A depending on how much they cut. We complained. Ultimately, we changed motor shops when they continued with the skim cuts.
Unlike most cars and modern motorcycles, Commandos do not use a wire wound alternator rotor. It is a permanent magnet device, with no brushes or wires attached. Your observations regarding increased clearance between the rotor and the stator are still valid.