I’m self taught. Most everything I know comes from experience. Keeping that in mind – I mostly mess with earlier motors. I also have a magnet charger. Some flywheel’s have the north pole marked. I would use a compass the check the ones that aren’t. (North pole of compass points to South pole of flywheel magnet.) Most often the North pole of the flywheel magnet passes over the coil first. I can change the polarity on the early magnets with the magnet charger. I could never see that it had any effect on the spark produced. Does it change which way the spark travels at the electrode like reversing the polarity in a battery ignition? Don’t know. If  you’re also generating current to charge a battery it may matter.  What is critical is the point where the polarity of the magnet changes as it passes over the coil so the magnet needs to be in the correct location in the flywheel. You might also experience some clearance issues between the magnet and the coils when you get it back together.

Tubs