I also have a NOS Yamaha regulator coming int he mail....I’m going to keep using 6V bulbs in my 400.

I found this in my files...

Sir,

Search for "Voltage Regulator" in the subject and "Hammer" in the author and you'll pick up everything, with pictures of my installation. It couldn't be simpler; yellow taps into the yellow in your wiring harness, and the brown is a Ground, and I just put it on the coil mount for a ground. The voltage is adjusted, if needed, via the adjuster mounted in the middle of the back of the regulator itself.

Hammer

Well this horse has got to be dead. Hammer I am using 6 volt bulbs and so is the original poster. The trail tech is for 12 volt ac. So to be clear if useing a 6 volt set up. (Headlight,illumination light, and high beam indicator light)
You will have to use a 6 volt ac regulator like mark posted in post #31 or the one wire rt325 posted on post #9. Also you have to hook into the blue wire that feeds the illumination lights to keep the 6 volt regulator from over heating due to not having the headlight on all the time to absorb the heat/energy. If I am wrong please please correct me so someone in the future won’t spend two days trying to figure this out.

You got it right... just to clarify though I highly recommend the Yamaha one-wire 6v AC regulator, I mentioned the 3 wire as a brand new reasonably priced alternative that DEET has confirmed to work... needed because several other regulators sold for these bikes have been confirmed to not work.

The 12 volt headlight/regulator is also a alternative solution that has worked well for many.

There are many threads on here with the same answers plus the Tech Library has the Yamaha Service Bulletin that details the headlight problem and the solution... (In fact the Service Bulletin link was given in the very first answer, post #2.) And I'm sure the same topic and answers will come up again and again.. probably not a dead horse... and it doesn't need to be... there's more than one way to skin a cat and someday maybe a better or different solution might show up?




.

My Yamaha 6v regulator showed up today and am waiting for
An H4 6v bulb that was recommended. I will report back ASAP.

Hey monel12 which regulator did you choose?

I haven’t received the other one yet. (The cheap one that was recommended). I should get it later this week, I hope. I will keep this thread updated, asap. Still waiting for the headlight bulb and the other regulator.

All,

I opted for the 12V as mentioned in my posts due to the large increase in light output. I'm not interested in keeping my bike stock, but building the bike I wanted in 1973 but couldn't afford on a military E-3s pay ($288 per month in 1973). So, I'll be reading posts like this, but as they say "listening, out" in radio parlance. I did not mean to confuse the issue in any case, just a simple, cheap source for light that's been available all along.

Hammer

Well, I just finished putting in the Yamaha NOS # 498-81910-60. I mounted the unit up under the frame (high) behind the horn mount....my pictures won’t show it. Just the wire running down to the connection to the main wire on the harness. Fired her up and went up to 6000 rpm...no problems with either the headlight bulb or the gauge bulbs......included in my pictures is the NOS and the Elcheapo from Fleabay.
Now, Waymee or Scottdove, if you want to try my Elcheapo, I would be glad to send it to you, before you buy 4.
Scottdove, I think you said you needed to buy 4. It wouldn’t hurt to try this one first. It’s new.
Thanks to Hammer, Mako, and all the others who chimed in with advice.....great forum! I’m taking this bike over to an open house at a local Yamaha dealer this weekend!