First, the black is ground of course. Red is power which lights the little bitch up. The green is the one that goes to the coil. I have no idea why ya have 2 other wires. I think someone here said that their bullet tach had 4 wires, but I can't confirm that. I can only speak for the 8,000rpm tach that I have.
I got some 18ga wire and extended all 3 wires under the tank down under the seat.
I used a quick connect for the black wire which had a washer type end. I placed this one on the right side bolt for the battery tray holder. Worked great for a ground.
The green I used one of those blue quick connect things for splicing into already runned wires. Not sure if you know what I mean or not. I spliced into the Blue, yellow strip with green dashes on it. This wire runs into the module under the seat. I did it this way cause the wire that I needed to splice into on the coil was too short and I didn't have enough room to fuck with it.
The Red wire I ended up making a "Y" connector with some 18ga wire and bullet connectors. I connected it into the brown wire in the harness under the seat.
Doing it this way I am able to disconnect everything without interferring with the stock wires already there, and it works great.