An aftermarket regulator/rectifier unit, make sure its both in one, and a small battery is what your going to need. With LED lights you can't just run the rectified and regulated DC direct to them as the voltage will still vary with engine speed and the lights will tend to flicker a lot without the battery to filter the DC power. I did one with a large capacitor on the DC output to help filter it, but it was a big cap, 120,000 uF, about the size of a pop can and rated to 35v. Worked great, guy still has it setup like that. Without electric start you don't need a big battery, you could get a cheap 7ah gel cell battery and find a place to put it, in the trunk if you have on, or make a small box to strap it to the frame somewhere. It would charge the battery and keep your lights steady, the added benefit is being able to flip the lights on without the engine running. I have two LED lights on my 200ES, they come on when i flip the light switch to HI beam, the Low Beam shuts off and they turn on. Two 27w LED's, one is a flood one is a pencil beam, giving me a good combo of close and far light.
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1984 Honda ATC200ES "Big Red"
1982 ATC200E "Hondie"
1988 TRX300FW "Project Quad" Still in progress....