[Zeke]

Good job. I wouldn't have thought that a key shift could alter the engine timing that much. However, it sounds like the flywheel advanced with inertia when the blade stopped. That would advance the timing and you had ignition knock. Good thing you didn't run it long. Bad things happen to pistons. I have a drawer full of kart racing motor pistons showing various damages.

That having been said, I suppose that motor is modern enough to not have points and condenser. I don't see any. It would have run if it had. They don't open using the flywheel.