I may be able to offer a little insight. I’ve had a 79 Kawasaki KE100 sitting in my barn for 30 years, pulled it out and got it in great shape and back on the road this summer. One of the most difficult parts of the revival was getting the lighting worked out.
The KE electrical system is probably similar to your TS, a three coil magneto powers everything on the bike.
- One coil powers just the ignition, the battery is not involved in that circuit at all.
- One coil powers the headlight only, with AC voltage, more on that in a minute.
- The last powers the directionals, tail lamp, brake lamp, horn and charges the 6V battery. Federal regulations required a street legal bike to have those items on a battery back then, not sure why the headlight didn’t have to be on it to.
Once I got it on the road the first ride (at wide open throttle and a blistering 53 mph) I blew the high and low beams in the 40 year old seal beam headlamp.
I found a 5 3/4”, 6V, H4 style headlight on Amazon with a 35/35 watt halogen bulb (the original was a 30/30 watt tungsten), I also purchased a 25/25 watt halogen H4 bulb.
With the 35 watt bulb the lamp is very dim at idle to just dim at high rpm, voltage measures approximately 2V at idle to just under 5V at high rpm and remember, this is AC voltage. With the 25 watt bulb the lamp is acceptable at low rpm to “it’s about to blow” at mid rpm, voltage about 4V at idle to 8V or so when I let off the throttle.
To save the cost of a regulator on the headlight circuit Kawasaki closely matched the load on the headlight magneto with headlamp wattage. Actually I’m sure they first figured out what wattage light was needed to be street legal and then built the magneto.
When you check the voltage to your headlight remember it may be AC, also remember you need to check it under load (headlight plugged in). Also if you change the load as in going to LED your voltage will climb significantly. If your headlight circuit is straight off the magneto and unregulated you’ll probably fry the driver before your foot’s off the kick-starter (ever hold the spark plug cable on a lawn mower and pull the cord?).
A quick way to check if your headlight is driven straight off the magneto is will it turn on if the engine is not running (off the battery)? If so it’s probably power by DC off the battery and your ahead of the game.
My solution for the time being is keeping the 35 watt bulb in, once I’m over 50 mph I can kind of see ok.
Next issue was the directional, tail and stop lamps. All 6V incan bulbs, dim, slow to light and directionals flashed slow, particularly at idle.
I swapped them all to LED, superbrightLEDs has a few 6V LEDs that fit with little modification but of course that led to a few other issues.
Of course the LED directional bulbs don’t draw enough current to make the flasher work. I could have gone with resisters but I was trying to cut the loads down so the battery would remain charged.
I found a 6V LED directional flasher on eBay but to install I had to re-wire the directional indicator in the speedo. Once that was done I turned on the key and everything worked great, directionals, brake light and tail light. I thought I was done until I started the engine.
With the engine running the flasher went nuts. Directionals off, the indicator would flash erratically at times. When I turned on the directionals sometimes they flashed normal, sometimes erratic.
Started testing with the volt meter and found my bikes simple, unregulated charging system isn’t very friendly to solid state components. The charging coil sends AC voltage to a simple rectifier (in this case just a single diode) then to the battery, no regulator. Since I’ve lowered the load with the LEDs as the revs go up the battery (and solid state flasher) are seeing more than 9V. And with the simple rectifier I’m sure if I pulled out the scope I’d see a significant AC ripple.
I’ve added a 25v 2200uF capacitor to the power line to the flasher and the directionals are working ok now. I’ll figure out a better recitifier/regulator to keep the battery alive over the winter.
As for the wiring on your battery, my 6V battery also has wires, positive is a bullet connector and negative is an eye. I bought a new battery and before I installed it I installed an SAE connector for a 6V battery tender.
Sorry for the long post, just wanted to give you an idea of what you may be in for it you want reasonable lighting on an old 6V bike.