I have a 1974 DT175 that I just got running. It's been converted to a dirtbike (no battery or lights), and I'd like to just put a headlight on it. Which wire coming from the magneto should I connect to and how do I control the voltage so it wont dim with different engine speeds? Thanks!

I have a 1974 DT175 that I just got running. It's been converted to a dirtbike (no battery or lights), and I'd like to just put a headlight on it. Which wire coming from the magneto should I connect to and how do I control the voltage so it wont dim with different engine speeds? Thanks!

Just a headlight? The yellow from the mag is the lighting feed on yours i believe, thing is it doesent work quite that easy. You need to regulate the voltage and that i believe on these is a resistor burried in the loom, a later voltage regulator may be a better option. You really want it switched too.

TBH bolting a decent torch on the bars will be as effective. And no i'm not being sarcastic even in good nick these headlights are really dire, an orangy blob 10-15 feet in front of you is about the best you can expect. The light on my mountain bike is as good.

Where could I get a voltage regulator that would work?

Where could I get a voltage regulator that would work?

E-bay is your friend,

http://cgi.ebay.com/ebaymotors/78-YAMAHA-DT-125-E-400-175-100-250-XT-VOLTAGE-REGULATOR_W0QQcmdZViewItemQQhashZitem45ef34a35fQQitemZ300365947743QQptZMotorcyclesQ5fPartsQ5fAccessories

I know its in the states but it came up in the first search.

Is the voltage DC coming from the magneto or do I need to run the line through the rectifier?

Is the voltage DC coming from the magneto or do I need to run the line through the rectifier?

No its AC, except for the electric start versions, and you don't need to rectify the headlight feed the bulb will be happy with AC or DC, just regulate it.

No its AC, except for the electric start versions, and you don't need to rectify the headlight feed the bulb will be happy with AC or DC, just regulate it.

I dont mean to hijack your thread, but i'm currently having problems very similar to what you guys are talking about in here. I have the same year and make bike, however the voltage is too high when the engine is running. I get almost 13 volts AC from it. Its blowing all my lamps as well.

Everything works well with a 6 volt battery connected (well except for the headlamp and some of the indicator lights). There is a small black sealed capsule (possible the resistor you're talking about) in the engine harness. Could this be bad?

Also how would i go about wiring a external voltage regulator such as the one you posted above?

Thanks!