My 71 Commando isn't charging. How can I tell if I need just a stator, or rotor as well? The battery is good, and the wiring as well. I'll admit that the alternator is likely an original.
Take the rotor off and try…
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Run the engine, in the dar…
Run the engine, in the dark, with all the lights on. If these do not brighten once the revs rise above 3000 rpm then the charging could be poor. Which can be a weak rotor or loose or broken wire somewhere in the system.
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Have a look on YouTube, th…
Have a look on YouTube, there are simplevideo tutorials how to check alternators. Lunmaddoes a good one.
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You should undo the stator…
You should undo the stator connections (it should be a 2-wire one on your machine) and using a meter, check firstly that it is not open circuit. You should see only a small resistance. If it is open circuit, it could just be a fractured wire inside the cable, so as a last resort cut it back and retest.
Assuming it is OK, run the engine and look at the AC voltage generated across the still disconnected stator wires. From memory, something like 17-20V should be expected
If that works, then the charging fault lies downstream of the alternator and in the rectifier/voltage control part of the system.
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Buy a new alternator and s…
Buy a new alternator and stator. Fit them. Then you're fine for another 40+ years.
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Al Osborn has kindly set u…
Al Osborn has kindly set up a page of useful electrickery info, section here on checking alternators: http://aoservices.co.uk/info/index.html
Regards
Mike
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Just found lunmad's video…
Just found lunmad's video, doesn't matter what make of Brit bike for this exercise, the application is the same.
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Take the rotor off and try to pick it up by touching it with a large screw driver flat on the top of the rotor, if you can lift it up using the screw driver the magnetism is ok.