The smoke's coming out of the air inlet after cranking and a failed start, not during cranking or running. She runs very smoothly when started and there's no smoke then.

I haven't altered the timing at all in over a year, she's been good there.

I had a problem with the old starter working loose and chewing on the flywheel...could an erratic force from the old starter have made the timing chain jump?... it's been rattling just a little slack for a second or two on startup for a while now.

I got the starter changed out hoping to solve the problem, but now there's a loud grinding at intervals when cranking that I had put down to a damaged flywheel (next job...), perhaps it's not the flywheel?