I have been looking at this idea for two days. The whole thing is very frustraiting. I have looked at tons of coils on line and have found quite a few that would fit behind the stock flywheel and put out 80 to 100 watts of power and they are moderately wound. There is no reason that someone who was in a good position to do so could not build a decent coil for the kx500. The E-line coil was the same coil from bike to bike just moded to fit. We need a coil that is made just for the kx500. after all the head scratching I have done I'm almost think a whole new ignition system would be the best way to go. The system that AJ from service honda had offered up would be the very best way to go in my opinion. We need to be thinking HID or LED as for a light source so theres no need for a big 200 + watt coil. If You want to run a halogen light on your offroad bike you are way out of the loop. There is no reason to develope a super high power coil for this, 100 to 150 watts max in my opinion.