I have had a charging problem with my FT500 since I bought it about a year and a half ago. One phase was putting out a low voltage. As a result the battery would go flat on longer rides.
I purchased a new aftermarket stator (Ricks Motorsport Electrics, Inc. Part# 21-135) and just finished installing it. The charging system now holds a steady 14.2 to 14.4 volts at all RPMs. I have to say this is an excellent product and very reasonably priced. It comes with all the wiring, connectors screws, etc. that you need to install it and it was a pretty simple install.