Motorcycle Repair: 1974 honda xl250, honda xl250, rectifier diodes

Question
-------------------------hi mark,
the serial # is xl250-2006822.  i traced the wire from the switch back to the alternator. it is direct, without going through the regulator or the rectifier. there is  a wire that tees off of the low beam power feed and is currently loose. according to the wiring diagram, there is suppose to be a resistor going to ground on that wire. could this be where the excess voltage is suppose to be going? if you don't have a copy of the wiring diagram, i could e-mail it to you.
thanks
dave
Followup To
Question -
hi
i just bought this 1974 xl250. the guy who owned it before me replaced a bunch of parts from another xl.  the headlight worked for a few miles, then burned out.  in checking the system, the alternator works fine. it has two stages. one for the headlight, and the other for the rest of the bike. the headlight side is putting out 30 volts. i think he left the voltage regulator, or what ever is used to reduce the voltage to the 6 volt range. can you tell me what honda used to reduce the voltage?
thanks
dave shideler
Answer -
Hi Dave,

Many older MC's didn't use regulators, instead they bled excessive voltage to ground via rectifier.

Do you have a service manual for the XL? Do you have a multi-meter? If so, check continuity of rectifier diodes. Current should flow in one direction; switch meter leads (switch polarity) and repeat test. No current (or very little) should flow this direction. If you get other readings, the rectifier is defective. Ensure a good ground exists where rectifier mounts to frame.

Try this and advise. We'll go from there.

Please send me the VIN or serial number from the frame. I'll check number for specific information.

Respectfully,
Mark Shively
mcso429@netzero.com
www.fop104.com


Answer
Dave,

I'll need to have the wiring diagram again.

The loose wire should be tight. It sounds as if you've found the problem or part of the problem. I'll look at the diagram and together, we can sort out what you have.

Me email addy will change to Roadrunner Wednesday afternoon. I'll edit and update AllExperts when I get home from work (sometime after 1700 hours).

I don't know what the address will be now. I'll keep Netzero for a couple of weeks. Just send here.

Mark