The tail light is intended for a chasis ground so it doesn't come equipped with a ground wire. All you have to do is run a ground from one of the screws on the light to the black/yellow ground on the bike. The other 2 wires coming from the light will be tail and brake, you'll have to test them to see which is which. Let me know if you need moreAny chance you remember how the wiring worked for the taillight? I am trying to wire mine and am having difficulties.. the aftermarket light has a blk and a red.. the bike has a red, a red/blu, and a black/yellow.. your bike is awesome and has partially inspired my build..thanks
Greg