The vinyl dye is good for seat covers. Bumper Black I never luck with, peels right off.
I have had luck with lacquer paint although it really doesn't make sense.
this is what I have done.
drain gas tank and leave the cap off for a couple of days.
used a razor blade to shave off any furry plastic < them wierd strings along side of a scratch>
scrubbed everything I was going to paint with Soft Scrub cleaner using a stiff brush on the scratches and a fine Scotch Brite pad on everything else.rinsed well and dried.
clean with acetone
masked and spray painted.since I had two different colors to paint and by dumb luck had one spray can of lacquer an one of enamel. Since lacquer will attack air dried enamel and not the other way around I painted the lacquer color first.
after drying applied PC Renew over everything.
I figured since lacquer is a brittle paint compared to enamel I figure the lacquer would crack and flake off and the enamel would peel. What I had afterwards surprised me.
The enamel pretty much just peeled right off as I expected but the lacquer is holding surprisingly well. I am wearing the paint off ,either by my pants, scrubbing the bike clean or scratching it by dropping the bike. Out of curiousity I bent my radiaor shroud seeing if the lacquer was cracking and it doesn't. I am assuming that the the strong lacquer thinners is "melting" the plastic a little. Providing of decent bond and some of the pliability of the plastic is leaching to the paint making a "flex additive" before it dries.
There was only a small amount of paint on the tank itself so I am not sure what would happen if you had a lot of the tank painted.
Oh and bythe way the bike hasn't had much riding time on it maybe 7 trail rides but the bike always has gas in it since I use it to dispense my lawnmower and wheedwhacker fuel.