I've come across a Motoplat Ignition for a 1991 KX500 or KX250 (the guy didn't know which) that is missing the plug wire. I can't find much info on these obsolete units. Supposedly some plug wires have a diode (red plug wire) and some don't (black plug wire). Does anyone know what I need to complete this unit or anyone that knows about these units? I'm at a loss.