Motorcycle Repair: XL250 Electrical Problem, regulator rectifier, haynes manual

Question
Hello,
I recently purchased a 1975 Honda XL250K2. The previous owner rode off road only & removed the tail light,
turn signals & battery. I am reinstalling the battery & lights to make it street legal. I have installed a new 6Volt battery & rectifier & tested the regulator & stator as instructed in my Haynes manual. When installing a new headlight
I discovered that the wire to the light is supplying 15 volts AC. Looking at the wiring diagram in my manual
I see that the coil in the stator that supplies the headlight does not run through the regulator/rectifier as does
the coil for the other lighting on the bike. Should this be 15 volts AC?? I'm afraid to plug in my new $60 dollar
headlight. Thanks for your help.  Darrell


Answer
Darrell, I checked an online wiring diagram and see that you will need to have a 3.61ohm resistor in the circuit to prevent overvoltage to the headlight bulb. I'm not sure where the resistor is mounted, either by the battery box or in the headlight mount/shell, but it looks like you definitely need to have one in the circuit. The headlight doesn't work unless the motor is running, thus the AC power on the wire from the stator going to the headlight switch. If the resistor is there, measure it to see if it is open or shorted out. The bulb is 6v rated, so 15v AC will probably cause it to turn into a flashbulb. Good thing you checked the power output first!

Bill Silver