Someone gave me aZ400,so I pulled it to bits to see if anything was useful for British bikes.The alternator is incredible.Its what is technically termed a brushless alternator,but of the type used in truck electrical systems.In short it has rotor coils that are stationary,inside a specially shaped one sided rotor.This means no brushes are required and the alternator can run in oil,and has a fully regulated output.Talk about advanced,compared to the stone age Lucas system,where all excess current must be shorted to earth.Normally you find the brushless system in alternators costing $500 to $5000 .Amazing in a bike that cost $600 new in 1975.Regards John.----PS Dont run without a battery.