Hi Mike,
I had similar problems with a Miller generator that I fitted to a Douglas special that was running on 12 volts. Having carefully cleaned the stator, I checked each coil for continuity and leakage to earth - continuity good and no leakage! On starting the engine, I got a good charge which gradually dropped off to zero. A second check showed a bad leakage to earth. A second clean and blow out with an airline cured the leakage, but starting the engine again gave the same result. After a lot of head scratching, I came to the conclusion that the engine the generator came from had probably suffered considerable wear resulting in iron particles being collected by the magnetic field in the generator coils - which eventually aligned and caused the short. I resorted to carefully dismantling the stator, unwinding one of the coils to check for the number of turns and guage of wire (20g). From a now not so reliable memory, I think there was about 230 turns in each coil. Anyway, I ended up winding 6 new coils (with everything encapsulated in resin). The rebuilt stator now happily gives an 8 amp charge (96 watt output from a generator that was originally rated at 60 watt!). During the build of the bike, I ditched the original rectifier and fitted a 15 amp solid state unit. The original units dont stand the test of time, and often consume more power than they pass.
Hope some of this helps,
Regards,
Eddie.
