Motorcycle Wiring Harness Kits | JPCycles Motorcycle Wiring Harness Kits. When it’s time to replace the wiring on your bike, or if you’re building a bike from scratch, never make do with any type of wires. It’s always wise to use a wiring harness kit for motorcycles––and only for motorcycles. Making a Motorcycle Wiring Harness The 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.