I recently added a couple of running lights to the rear of my bike and was required to add some new circuits to the wiring harness. Over the years I have seen some very strange wiring additions, and most make it almost impossible to go back and trouble shoot at a future date. I have a trick that might help you here.
If you have ever opened a computer up you have most likely seen what are commonly called “molex” connectors. These are pin and socket type connectors that generally have three to six circuits running parallel in a flat nylon body. They are used to route low voltage cables from the system board to HD's and CD's. Well these molex connectors come in many forms, some of which are rated at up to 120 volts and five amps. They generally will fit up to about 12 gage wire, and come in all number of circuits, making them perfect for rebuilding a motorcycle wiring harness. The one short coming is that if you buy a standard connector, you have the same number of circuits coming in as going out.
Now here is the trick. You can create one standard wire contact, and a number of “dead-end” contacts that end just beyond the back of the molex connector body. You can then put a wire, or thin metal plate in contact with all the contacts and solder them together. This makes one contact share power or the return to ground, with all the contacts. Being of a flat surface design, the molex connector blocks are easy to label so remembering what goes where is not a problem. If you really want to get creative you can make one circuit branch while others simply act as a butt or pass through connection.
The pin and sockets terminals are small enough by themselves, to make very neat bullet type connectors that are easy to route through small openings. A little solder and heat shrink tubing is all you need.
I think that my humble drawing will give you an idea what I am trying to explain. The photo is of three molex terminal blocks, all of five circuits branching down to one. One connector block covers the brake light circuit and its branches. One block covers the tail light and tag light circuits. The third is the ground or return circuit pathway.
If the wires need to be replaced or removed from the terminal block you need only use a simple extractor tool that is available where you buy the terminal blocks.