wiring DT2 250
I think that the regulator should be wired into the blue in the headlight shell and it should also be earthed - see the Yamaha Service Bulletin in the Tech Library.
I found a 6V Yamaha regulator on Amazon for $20, connected to dark blue wire in headlight shell and grounded it and verified that voltage for both high and low beams doesn't go over 6V when revving engine, which was not the case when I was blowing $40 headlights. I originally thought about connecting to the yellow, but then I would be putting load on regulator when headlamps were off.
Aubs wrote: Hi all, I have issues with my ex USA 1973 DT2 250. Headlight bulbs keep blowing on long runs and I believe the present wiring is incorrect. The handlebar dip /main beam switch carries the earth to the bulb holder. Is this correct ?. I have fitted a regulator onto the yellow from stator but bulbs are still blowing. Looking forward to your replies.
I'd like to hear more about your switch wiring. The bulb should be earthed and the switch should provide power to the filament selected.
Aubs wrote: Thanks Mark. I thought as much only I didnt wish to go into ignition wiring without confirmation . The handlebar switch also carries the earth to horn which I feel certain is correct. I however was not sure that the switch dip/main beam and horn were insulated from each other. I am having difficulty in finding a close up wiring diagram of the ign. switch so do you know the colour wire from ign. to dip/ main beam switch.
If you go to page 109 of the combined 71-73 DT/RT Service Manual in the Tech Library, there is a "legend" that shows the connections when the ignition switch is in a certain position. As you need the ignition switch in position II for lights, looks like red, brown, blue are connected.