I had a similar problem a few years back with my nsr 250 mc21.

One day I was riding my bike and the next nothing. I replaced the pgm box and I was back running again. Then a month later it happened again. To cut a long story short there was a crack in the coil that was hidden underneath the rubber strap that supports the coil. My guess was the coil was causing a short and feeding back to the PGM. I had a friend that is very clever with electronics, so we tool apart my broken pgm and discovered a burnt out component that help charges the coils. The bad news was that they fill the pgm circuits with this wax plastic stuff that is a nightmare to get out but we managed to replace the burnt out commpoents by soldering the new component to the legs of the faulty one. Plugged it backing and fantastic it worked.


Jamie