I think there's a coil in the flywheel. And then there's your two ignition coils, one for each spark plug. Those two coils have to sit within +/- X distance of the coil on the flywheel. As the flywheel spins, it creates current in the ignition coils. Too big a gap, little-to-no spark. Too small a gap, your coils grind together like a lathe.