Barely any light output... I have two new/old stock lighting coils yet to install. But I'm wondering if it's the ignition or something else that I havent checked.
Grounds checked
Rectifier checked
6v Bulbs checked.
I've omed the living crap out of the wires... fixed breaks in the whole harness.
I'm almost certain it would be the lighting coils right?! Battery or no battery still get some output of light. The more rpm a pinch brighter it gets... not enough to be road worthy though.

If it would be the coils any tips and or tricks on replacing them?

I'd suspect high resistance in wiring, connectors, and/or switch contacts.

Ohm test won't reveal that kind of problem, especially if using a digital meter.

You can test for voltage drop across connections... easiest to temporarily use a powerful 6v battery or power supply to power the headlight circuit and check voltages along the circuit with headlight on. You might find something like at battery there's 6v but at the light there's only 3 volts.

Again, it is important to do the testing with the headlight on... with no load, the voltage drop might measure at or near zero... The larger the load the more the resistance in the circuit will drop the voltage.

With the headlight on and the system under load, you can also connect a voltmeter across each connection/switch. Say one lead to the "in" wire on the headlight switch and the other meter lead to the "out" wire on the switch.... (you need to leave the switch completely connected, headlight should be on...) Ideally, the voltmeter should read 0. Whatever voltage you read on the meter is the voltage drop across that connection/switch.

Make sure you have 6 volt bulbs & not picked up 12 volt. If it were me [with a box full of old bulbs] i'd unplug the mag loom but leave the black so the ignition will run the bike through the switch [or just run the black direct to the plug coil although no way of topping it in event of a stuck throttle]--your call. Then pick an old 12 volt bulb & hook it to the yellow & see if it lights up the street. If its still pittifull dull then try a 6 volt. Although by this time it might be a good idea to check the unloaded ac voltage output. By the way, the lower the wattage of the bulbs the brighter the light--I.E. 25/25 will be brighter than 35/35 in the headlight. * don't get the tail light bulb cross wired ot it'll be running the high wattage brake light filament [well would be down here in nz] but in the us you might have battery powered tail lights? but even if so then the charging system is still trying to keep the battery up to keep 'that' light shining.

Just thinking back to the "80's i had an XJ650 huge headlight on my ride to work RT1 & had possibly the original XJ bulb in it which might've been 60/55 & could rev it hard but never blew the bulb & man it was bright at revs [not at low revs]. Had no charging system or battery just head & tail lights nothing else.

I thought I would add a word of advise here. If you are going to use a external 6 volt dc battery to do some testing on the lighting circuit as Mark has suggested above a word of caution. If you have a 6 volt ac voltage regulator installed in your system you will need to disconnect it from the wiring system to do such tests.
If you don’t you’ll get some electrical smoke and melted wires. Ask me how I know.

Very good point!!! AC regulators are not compatible with DC. An RT1 didn't come with a regulator but could have had one added. Thanks for making this important point!

So old thread but... I got the wiring figured out now I have brake lights, high and low beam, need to get a flasher relay now and the shifter teeth on foot peg or shaft are stripped (haven't looked yet) but now problem is trying to get a good battery, flasher relay, and figure out the shifter. All in all almost road worthy.

Well it looks like the shifter shaft is "ok" but the foot shifter doesn't look good. Is it feasible to put in a longer bolt so I can get a nut on the end to grab the teeth tighter? Or any aftermarket jobbies work?