My RT3 came with the wiring harness and most of the electrical fixtures in a box. I cleaned up the harness and wrapped with fresh tape and sleeving. I think I have the routing correct and everything except one wire is spoken for. Two questions I’m hoping you RT owners can answer. There is a black wire with a large round connector in the very last group of wires at the end of the harness. Wondering where it connects. I thought it might be a ground for the rear turn signals but there is only one so ?? Next, there is what looks like an after market regulator spliced into the yellow wire coming out of the key switch. I recall hooking regulators into the blue wires in the headlight. It’s a lousy splice soldered at a 90 degree angle to the yellow wire. A slop tape job would be questionable. Any thoughts would be appreciated. Wish photos we’re working 

Is that black wire an integral part of the harness, or is it connected to the harness with a bullet connector?

Yamaha regulator fitting instructions say to splice into the blue wires in the headlight bucket (but you probably knew that already!), so go with that. To save messing with soldering or two into one crimping, I made up my own pigtail extensions, male at one end and double female at the other.

Hi Al, it’s integral with a fairly long wire and a closed end circle connector. There is also a short jumper wire coming from the bottom of the battery box which seemed the right length for a black with a male bullet that is with the reds and browns mid harness. I think I’ll eminate the regulator that is spliced in to that yellow and go with a known good part and connection sequence. It looks like a regulator that came on a TS250. 

Not sure about the black wire with the eyelet myself if someone could elaborate I would appreciate it.

Don't quote me but the only one i can think of is the loom earth which screws to the coil mount under the tank. They all earth to there by memory. Welcome from NZ if you're new.