How is this for cool, I used to have a goped scooter with a 50cc Shindiawa clone engine on it. I got an add on electric starter that was very interesting. It had no moving parts, and was just a stator coil that went over the magnetic flywheel, so it shared the engine's crankshaft, in a way, it turned that directly. But what else was cool about it is that when the engine was running, it produced 14vdc, as a generator. So what I did was I wired a big diode in between the battery, and the stator, that blocked power from going from the battery to the stator, and the starter button simply bypassed it. The negative of the diode connected to the positive on the battery, and the positive on the diode went to the positive on the stator. The diode would allow the stator to charge the battery, as long as the stator voltage was higher than the battery voltage, but not the other way around.