Well, the piston arrived, I fitted it and rebuilt the engine. Compression was *much* improved. I tried to start it and whilst it tried a few times it then stopped entirely and was basically dead.
Taking it to bits showed no spark. Meter out and more of the bike in bits. Kill switch was fine, power was obviously being generated from the lights, tested the ignition pickups and no continuity to the ECU on one of them. That’d do it.
Found the broken wire where the cable was wedged between the airbox and the frame, fixed it, bike started first kick. At this point it was 11pm and I don’t particular want to upset the neighbours so I’ll leave a test ride until the morning. It was smoking nicely which was expected.
It looks highly likely it died due to the broken wire and not the piston which makes more sense. Nice to have found the piston before it disintegrated!
I just hope I’ve fixed the gremlins, the bike tests successfully tomorrow and I can play on Friday! 🙂