I've got no spark. I bought a new ohm meter today that I can set at multiples of one/ten, so will take it from there. I also have a '77 Yamaha 400 which may (or may not) have an interchangable stator plate. I can get a used CDI for $75 at a motorcycle scrap yard here, but can only test it, on the bike, there. My truck got rear-ended, and my bumper hitch is bent too low to pull my trailer, so I'm kind of screwed until the DrawTight hitch I ordered arrives, or until I get the insurance co. to fix my (work) truck, which I use daily. It's a pisser!
I understand how things make other things move mechanically much better than I understand electrical "black box" stuff. By 'source coil' do you mean what my Yamaha manual calls 'charge coil', which puts a charge into the CDI, as opposed to the pulse coil, which sends a jolt to the ignition coil?