Motorcycle Repair: ignition coil, exhaust stroke, dual ignition

Question
I recently put a used engine with a dual ignition coil into a frame that had a single ignition coil now I don't have a spark on one plug ,what is the difference in the firing?

Answer
The dual coils required two sets of points to fire them and the plugs fire individually.  The single set of coils fires both plugs at the same time but one plug fires on the exhaust stroke.  I'm not sure what model bike we're talking about but if the pistons go up and down at the same time, a single coil setup will work but if the pistons alternate 180 degrees apart you'll need two coils to get it to work. I'd guess if you took the plug out of the cylinder not running and laid it on the head you'll see that it's firing but not at the right time.  

Regards,
Rich