wow, so many replies, in such short time.
look at homebrew wind power for your answer, there are a lot of people using car alternators to generate wind electricity, and the car alternator is the same basically as the cb750 alt, you need to bypass the voltage regulator and power the exciter coil directly from the rectifier output, thus it will begin to magnetize the rotor when it starts turning. you also need to add a "primer" magnetic field to the rotors, the wind people were using a small magnet sunk into one of the rotor "fins", that would produce a small voltage just to get the whole thing started before it cascades. if i were doing it, i'd find a ring magnet that would fit around the bolt that holds the rotor on, something fairly flat. but that's how i would do it if i were trying to do it your way. honestly, I'm working on a lightweight carbon permanent magnet rotor, which will remove the whole rotor from the engine, which weighs something close to a battery, and this should reduce the flywheel effect also...
