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wiring DT2 250

20 Nov 2020 01:11
Aubs
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wiring DT2 250 #1
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.
Aubs.from Wales.

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20 Nov 2020 01:45
Gr8uncleal
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wiring DT2 250 #2
Aubs.

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.

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20 Nov 2020 10:59
msavitt
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wiring DT2 250 #3
I had same issue
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.

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20 Nov 2020 12:38
apex
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wiring DT2 250 #4
You didn't say it, so you have to have a good battery as part of the lighting circuit, and all 4 lighting bulbs (tail/instrument/headlight) need to operate. Any break in this chain potentially overloads the circuit. Regulator should be on the blue wire, not the yellow.

Allrighty Then

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20 Nov 2020 17:21
MarkT
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wiring DT2 250 #5

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.
Aubs.from Wales.


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.

1963 YG1-T, 1965 MG1-T, Allstate 250, 1970 CT1b, 1971 R5, 1973 AT3MX, 1974 TS400L, 1975 RD350, 1976 DT175C, 1976 Husqvarna 250CR, 1981 DT175G, 1988 DT50, 1990 "Super" DT50, 1991 RT180, 2017 XT250

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21 Nov 2020 01:29
Aubs
Mini Enduro
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wiring DT2 250 #6
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.

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21 Nov 2020 04:40
RT325
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wiring DT2 250 #7
If its blowing on long runs i wonder if its a vibration thing with the bulb or sealed unit 'hot' filament just dropping off. Normally if it was going way over voltage one good rev would blow it. Is any of the other bulbs blowing at the same time that run off the mag like usually instrument illuminating lights & high beam indicator light if fitted. Is the tail light run on DC on yours? as in NZ where i an the tail would be AC so Blue & i've run the regulator into that wire because it gets everywhere the blue goes. Mind you on that theory blue is blue & wherever it is then you could hook the regulator wherever is convenient. Yellow from the stator would/should fix it but probably overloads it with lights off as you say. Black is earth & the loom earth ends by the plug coil under the tank--i think. If the earth was faulty i think it would just stop the light not blow it. Good battery should be fitted but even so, if the regulator is working it shouldn't matter if the battery is out of it from a headlight blowing point of view. Sorry, not telling ya anything you didn't know already. Test the ac voltage to the bulb high low wire with the regulator on & off & see what you get, just to be sure it's limiting voltage. Unhook the battery & see if it hold the voltage in check to the bulb. Welcome from NZ by the way. How's Wales, still locked down?. Also, just reading again--yours is or should be a DT2 if you're looking for bits as DT250 started in "74 & totaly revamped engine design & frame, although i doubt the wiring is much different as still magneto on the 250. The 360 changed to cdi in "74 so far as spark goes.

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21 Nov 2020 05:20
Gr8uncleal
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wiring DT2 250 #8

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.

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