Battery Any Way to Make AC Power Wire Charge a Battery?

[Msomma12]

Hello all, I am currently working on a vintage scooter and I am having some trouble electrically. I put an engine meant for a newer bike onto it and the wires that come from the stator of the new motor don't match up with the wiring harness of the bike. After getting the ignition to work, I am left with one wire from the stator. When the bike is idling, this wire provides around 20 volts of ac power. When revving the bike, it gets to be over 100 volts. Is there any regulator/ rectifier that someone recommends that can take this power from a single wire, convert it to 12v DC, and output the power to a single wire to charge my battery?'

Thanks a lot, any help is appreciated.