Jim,ask around for people that have used auto paint on a Harley motor.I get mixed reviews.It will stick no problem if you prep it right,but Harleys are hard on paint.I'm not sure how long the heads hold up.I won't powdercoat my motor since it's air cooled and the powdercoat just helps hold the heat in.It's bad enough she gets cookin' in traffic,I sure don't want to add to the problem.Running an oil cooler won't help the heat much either.They're useless in heavy traffic and only work if you're moving pretty well down the road.I know it looks like hell,but the best finish is a natural finish or the thin black,but the black always goes to crap.Don't use brake cleaner on the black either,it eats it enough that one time it'll finally start coming off and keeps peeling back.