Finishing up a 1975 DT 400. All the lights work, but when I rode it last week, it blew out...I know there is no regulator on this bike, and is controlled by the battery, but this is the second headlight I have blown.
I also blew a couple gauge bulbs earlier...just put new ones in, they seem pretty bright when I started it up today in the shop....
Help? Suggestions?
Jim

Here is the service bulletin for wiring in a voltage regulator (if you decide to). It also lists 8 reasons why headlights can blow out.

www.yamaha-enduros.com/index.php/worksho...ulators/viewdocument

Thanks, Devin.

Geeez, there’s a new one on Fleabay, for $174.00!! Anything else I could use in place?
Jim

monel12,

As the headlight is AC, and produces prodigious amounts of current (hence the blowing bulbs), you may want to consider converting it to a 12 volt auto-type H4 bulb and a voltage regulator. It's a simple install, and I went with the adjustable voltage regulator which allows me some leeway in voltage. It's been documented here more than once, and should be easy to find with the search feature.

Hammer

Thanks, I will look into that solution.
Jim

monel12,

See my message to you!

Hammer

If it's a std system it sounds like the rectifier isn't working to soak off the excess to charge the battery. Another 'unlikely' possibility but unlikely in this case is if say it's designed for a 35/35 headlight & you went to a 15/15 it'll probably blow even with charging system working as lower wattage bulbs give brighter lights on an ac system. Don't think they make 15's in the large base bulb & i'm talking small bikes [old bikes]. Hook a regulator into the yellow from the mag or the blue after the switch in the headlamp?. [correct me if i'm wrong]. Any old single wire yamaha regulator will work. IT250 or any IT finned alloy ones are good.

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