I just bought a DT175 in Botswana. The bike comes from Yamaha South Africa. The headlamp dims so much when I apply the brakes, regaurdless of speed/rpm, that I can hardly see where I'm going. If I use my indicators, it does the same thing and when I use both, the light almost goes out. I managed to measure, with no other lights on, a 50 mV voltage loss on the negative side of the bulb and 450mV on the positive, making me suspect that the earth is good and they should have simply used heavier guage wiring from the factory.

I would like to change the 165mm x 100mm headlamp with a standard, e-code headlamp housing anyway, which would require a different bulb base like the p43t of an H4. This means that unless I can find an H4 in 6V, if they even exist, I might have to attempt a 12v conversion. I'd get less voltage drop, but unless there is a more robust stator that will fit this bike I might not get much of a charge on the battery below about 3000rpm. Otherwise, if I can find a 6V H4, I will just work out heavier guage wiring where it's needed and use 6V H4 globes. That would raise another question: anyone know how much current this magneto is able to produce? And is the headlamp circuit completely separate from the rest of the lighting system?

Thanks for any insight on these matters! Keep well!

I just bought a DT175 in Botswana. The bike comes from Yamaha South Africa. The headlamp dims so much when I apply the brakes, regaurdless of speed/rpm, that I can hardly see where I'm going. If I use my indicators, it does the same thing and when I use both, the light almost goes out. I managed to measure, with no other lights on, a 50 mV voltage loss on the negative side of the bulb and 450mV on the positive, making me suspect that the earth is good and they should have simply used heavier guage wiring from the factory.

I would like to change the 165mm x 100mm headlamp with a standard, e-code headlamp housing anyway, which would require a different bulb base like the p43t of an H4. This means that unless I can find an H4 in 6V, if they even exist, I might have to attempt a 12v conversion. I'd get less voltage drop, but unless there is a more robust stator that will fit this bike I might not get much of a charge on the battery below about 3000rpm. Otherwise, if I can find a 6V H4, I will just work out heavier guage wiring where it's needed and use 6V H4 globes. That would raise another question: anyone know how much current this magneto is able to produce? And is the headlamp circuit completely separate from the rest of the lighting system?

Thanks for any insight on these matters! Keep well!

That sounds like a bad connection or a bad earth. Most probably the latter.

Are U sure U want to drive in Botswana at night? I put spotlights on my bakkie and still cannot see the donkeys or the cows.