There's nothing much to photograph yet. I only got started tonight. I've been too busy tuning and riding for a few days.
I got as far as working out how to mount the motor, (hereafter called a generator), probably just above the jackshaft, it fits like a glove and the approximate gearing to start with, about 8:1 or 10:1. That's just doable in the space. (At 10:1, the generator will be spinning at 1.4 times the speed of the motor. Might be too fast yet. At 7000 engine rpm, the genny will be spinning at 9800RPM. Trial and error will get things right.)
Incidentally, this method has one drawback - it will only generate when the bike is moving. ie The clutch must be engaged to turn the jackshaft, so the battery must carry the lights while the bike is stationary. Not much of a problem.
The generator is small but gutsy, as a motor it uses about 120W under load, (10A @ 12V). It came from a 12V portable compressor for pumping up car tyres.
It's 57mm x 36mm, with a 3mm shaft that has a flat spot for a grub-screw.
Should go close to doing the job.
For now, at least, I'm setting up with plastic pulleys and a belt, but I'll have to get metal pulleys if it works OK. I'll probably mount the drive pulley on the side of the 17T sprocket, or hard up against it.
I haven't thought about the regulator yet, but that bit will be easy. I want to ensure that I can get usable power first.
Pic of the motor below.
... Steve