[hugojose]

Regulator/Rectifiers generate heat, thus the fins. Depending on where is located in a motorcycle, whether is more or less exposed to flowing air, would make temperature varies. Some riders have reported 200F, measured with an infrared thermometer.

.....all that said, current is what relates to temperature. I'd start by checking charging voltage (about 14VDC), and then check for any loose or corroded connection which would increase current consumption, starting with the battery connections.