I have a 1974 dt 360 that runs great but gets to much voltage to the headlight causing it to blow. I thought this happened because I ran it without a battery but even with a battery I am getting almost 12 volts to the headlight. is there a voltage regulator or something I am missing that could have gone bad or is t all built into the cdi?
thanks for any help anyone can offer I really want to get this bike on the road

Service Bulletin #M5-084 re Voltage Regulators

Download it here: yamaha-enduros.com/index.php/service-bul...e-voltage-regulators

Yamaha discovered the problem but didn't solve it on US production models until 1976.

is there any alternative regulators that can be used that are not $180 that you know of ?

Yes. The stock regulator for the later models work fine and are often available on E-bay.

One of our members, Rex's Speed Shop has one for sale for around $30 - I have one for testing but have not been able to do so yet. His other products work really well, so I have no concerns with it. yamaha-enduros.com/index.php/forums/want...-now-available#15209

There are some others that are harder to find, and a lot of cheap ones designed for Chinese scooters that fail. Either option above are good choices. I would tend to go with Rex's mainly because it would be new as opposed to untested used and they are about the same price as most used ones go for.

so the bulletin shows bolting this to the headlight shell is that earthed enough? and fro what I gather because im not very good with electrical technical stuff, this will be spliced into the blue wire in the headlight that goes to the speedo and tach and a back wire is to be made and connect from the headlight shell to the black wire that comes out of the headlight. this may be very simple but I just like to know how things work so how does this prevent over powering to the headlight and battery ? also do you know of any good replacement headlights? as mine blew during this and all my dash bulbs and tail light bulb

That sounds correct - you just want to make sure the regulator splices into a wire that is hot with the lighting, either on high or low beam. The ground to the headlight shell is fine if your shell is grounded!

The choice to mount on the shell is in part for cooling.

Here is a link to a decent quality headlight I got off of EBay.

pages.ebay.com/link/?nav=item.view&alt=web&id=351277621105

Decent price and quality. If you can find a #4020 headlight, that is the best solution though hard to locate.

thank you for all the help I located a 4020 and put all new bulbs in new rectifier and regulator in I spliced it into the main lighting blue wire that comes into the headlight shell as the bulletin said to do and so far so good getting 6.2volts ac to the headlight and when revving I got 8 volts to the battery. now to replace these original tires from 74 and new fork seals and I think im ready for the road

Sounds like you are well on your way! We of course will need pictures . . .

Hello there,

Im hoping this topic is still going and someone will see this...
I own a yamaha dt 360 1974. I want to keep my 6v system and im having issues with my headlight and tail light blowing. I found a 6v regulator and attached it to my yellow wire coming out of my mag and on testing it seemed find but as soon as I put my 6v headlight it in blew and then down the road it blew my taillight. On reading this do I need to splice onto a blue wire? Does it matter where I splice it?

Regards,

Rudy

Pics might help if possible sometime but from my longterm memory blue goes everywhere including headlight when lights are on as blue goes into the dipswitch to power high & low beam green & yellow wires. Seems odd if your tail light lasted a bit after the headlight blew. Is your tail ac off the mag or dc from battery. Ours run ac tail & headlight plus instrument illuminating bulbs. Hope ya not blowing expensive sealed headlights. Luckily we have replaceable bulbs [in NZ]. ps, i used to connect the single wire regulator to the tail light blue but mostly i was 'not' using a battery. I could be corrected on this though.