Running backwards? The crank must be in upside down. Or maybe you should remove the wheels, turn them upside down, and reinstall. Or maybe you are kicking it over forward instead of backwards.
(Just kidding :) )
I guess if you were playing with the timing and replacing the stator, you must have had that stator cup off, so you would have seen a sheared key... unless you sheared it on the last install.
Was there any debris on the rotor magnets from the previous failures? And just thinking out loud, I wonder how the bike detects the crank position? Hall effect sensor? Magnetic switch? Waveform from stator? On my Buell it's a hall effect sensor, and it doesn't seem like the stator output would be a reliable trigger. But it must be something on that stator, because that's what you turn to change the timing...