Motorcycle Repair: coil, exhaust stroke, coil works

Question
What's a single-fire coil?

Answer
A single fire coil works with a single fire ignition. Harleys work with a duel fire ignition. What that means is both cylinders fire at the same time and on the intake and exhaust stroke. the problem is that the rear cylinder is in a different position as the front cylinder due to the fact that the motor is in a V. So the coil fires both cyclinders at the same time.
A single fire ignition fires each plug at the time when it needs to fire, so you need a single fire coil. Baically a single fire coil is two coils in one.
Good luck and happy riding
Mike