Motorcycle Repair: Headlight Burning Out

Question
Hey Bill,

I have a 1975 XL250 and the headlight is burning out. I've done quite a bit of reading online and have a fair idea of how the power gets to the headlight. My understanding is that it's AC power straight off the stator. Including on your site, I've read about the existence of a 3.61 ohm resistor that helps to maintain proper voltage to the headlight. Funny thing is, I think I know where the part used to be on my bike. If I'm not mistaken, it's a small harness that comes out of the back of the headlight with a white wire. On my bike, there used to be a small, cylindrical thing attached to that harness. It was about two inches long and the diameter of a pencil. It seems to have "left the bike on it's own." The harness is still hanging there, just no resistor attached anymore.

Could this be my problem? Assuming it is my problem, where in the heck can I find a replacement part? I'm just not having any luck finding anything but rectifiers and voltage regulators. I saw where one guy tried to make one with a modern day resistor, but he wasn't having a lot of luck with that. Any ideas?     Ken

Answer
Ken, yes the resistor is necessary to control excess stator output current.

Lucky you..... They are generally hard to find... 35400-329-671 is the part number

http://www.ebay.com/itm/NEW-NOS-OEM-73-78-RESISTOR-CT-MT-XL-RESISTOR-35400-329-6

Bill Silver