The more I research, the more confused I get so I guess I should just come out and ask.

‘73 RT1-360. No battery, no regulator. I know it’ll blow bulbs, expected that to happen. I was under the impression 12v bulbs would last longer. Not! So I guess I need to put a battery in to eliminate that problem. Isn’t that the reason the factory did it?

I need to replace the tail light assembly because the aftermarket one has the lens missing and so far I haven’t been able to find one. Can I run 12v LED? Is it it plug and play or will I have to do something special or should I look at something else? I’m not real concerned about brightness, just want it street legal enough to get to and from trails.

Any help will be greatly appreciated.

I might confuse things but yellow is the lighting wire from the stator but there's a couple of other lower output wires you could experiment with. Not sure but easy to find out of the stator loom, Forget black, that's spark, So yellow ,possibly green with red tracer, then a straight green. I'm looking at the colors on an RT1 1971 so not sure if colors changed by "73. You could run a single wire regulator into the yellow then run 6 volt bulbs & they'll be bright 'as'. You'd have plenty of spare '6 volts' to run a 6V 35-35 headlight possibly. I'm forgetting you're running sealed units in the US. We have replaceable bulb type in NZ. I found a 12 volt AC single wire Honda regulator in my parts. I know its Honda as has a green earth, -- yamaha earth through the regulator body but same outcome. So--was thinking 12 volt bulbs & one of those regulators off the yellow stator wire, but don't know that you'd end up with better lights in end & maybe weaker at low revs. I recently bought some 12 volt 35-35 hallogen bulbs off Aliexpress for my quad which has the same fitting as my old AT1 & all the other smaller yamahas. Cheap as chips with free shipping, but not tried them yet.

For the low cost of 6v batteries, I would buy one. You might also find that a 12v headlight bulb will then be able to carry out the same function as the 6v regulator.

Regarding the rear light, I'm not sure exactly what is missing - lens here in the UK is not quite the same as in the US (just the plastic cover here). Anyway, have a look on Partzilla or CMSNL for the missing part(s), select the item and both sites will show which other models used them - you can then expand your search accordingly.

You might find yourself having to buy, say, a complete rear mudguard and light just for the lens. No problem though, just sell on what you don't need and you might even cover your costs.

RT325 - You did make things more clear. The more I looked at the wiring diagrams, the more I didn’t see what I was looking at. This bike is basically a hybrid, a cross between a RT3 and a MX. Engine and frame numbers match. It does not have an ignition switch or a mount for one so that complicates things a bit. Thank you for straightening things out.

Gr8uncleal - My best bet will be to replace the whole assembly. I just don’t know if a 12v LED would work or not. This is what I have now

Get a 6 volt regulator in the system to absorb the voltage. I am running 6 volt LED headlights and 6 volt tail lights I think the number is 1154 with voltage regulators on DT1's RT2's and dt 360 and 400's and with the voltage regulator I have no problem. Connect to the yellow coming out of the stator and make sure its well grounded. Not sure how accurate you can measure voltage from a stator unregulated but my digital meter was flashing momentarily 34 volts when you rev the engine up to 6500. I fried many bulbs learning the lesson.
Doug

Get a 6 volt regulator in the system to absorb the voltage. I am running 6 volt LED headlights and 6 volt tail lights I think the number is 1154 with voltage regulators on DT1's RT2's and dt 360 and 400's and with the voltage regulator I have no problem. Connect to the yellow coming out of the stator and make sure its well grounded. Not sure how accurate you can measure voltage from a stator unregulated but my digital meter was flashing momentarily 34 volts when you rev the engine up to 6500. I fried many bulbs learning the lesson.
Doug