As you seem to have an intermittent ignition related problem, let me tell you a little story.......... Some time ago my GS developed a strange intermittent problem, sometimes starting and running perfectly, but then I'd stop for fuel or something and it wouldn't restart. Loads of pops and bangs, huge flames and misfires from the exhaust, great sparks at the plugs, but would only start after loads of churning and 'easy-start' or if left while I went and had a medicinal beer. Whether the engine was hot or cold made no difference, and the problem just came and went with no discernible pattern. It nearly drove me insane finding the fault. Having a complete spare bike, I finally swapped EVERYTHING (complete fuel tank and pump, spark plugs, coils, leads, hall sensor etc.), and the problem would still crop up. I finally tracked it down to a very small magnetised piece of metal on the timing wheel that triggers the Hall sensor (and spark timing). Sometimes it stuck to the Hall sensor and had no effect, and sometimes it stuck to the wheel and span round giving false ignition sparks all over the place. Removing the piece of metallic grit solved the problem completely. So simple, yet so difficult to find...............
