Re: Over Charging Problem
First off, I would stop throwing parts at that motor, that can get expensive. Do you have a manual? If you dont, getting one would save you unnecessary purchases in the future, and will pay for itself a million times over. You purchase the Rectifier and Regulator assembly together, #0585195on the 25 in. model. Have you tried manually testing the voltage across the battery to ensure that the gauge is not faulty? Another issue could be high resistance between the battery and terminal in connecting leads. Are they corroded at all?
If you have an unregulated system, they will do that. Some batteries work better with unregulated systems than others. Sometimes newer batteries solve the issue. Unless you make very long high speed runs you have nothing to worry about. If it bothers you, turn on all the lights and accessories you can. Voltage should drop a little, and keeps from overcharging the battery.