Making a Motorcycle Wiring Harness - liveabout May 23, 2019The wiring on classic motorcycles is relatively simple. Making a new wiring harness, or rewiring a classic motorcycle, effectively starts with one wire. The mechanic should start to place the various wires on the bike, attaching labels to identify the location. Simplified Motorcycle Wiring Harness | MotorcycleZombies May 21, 2019Materials Needed to Build a Simplified Wiring Harness. Before you build a simple wiring harness for your motorcycle, you’ll need: Enough new wire – 16 to 20 gauge stranded copper wire. New bullet (single, double, and triple) and fuse connectors – remember to grab male and female. Battery. Battery ground wire (4 to 6 gauge).