Also here is a tip use Dupont plastic prep and follow the directions that is the only way that you can get the paint to stick Believe me when I painted my first Fiero (plastic body pannels) I did not use it and the paint did not stay for more than 2 years, since then I use it always on each Fiero I paint
For what it's worth, I used PJ1 Yam Blue paint a couple months ago. It came off as soon as I hit it with contact cleaner. You may want to try the clear coat they recommend - I didn't but will next time.
The yamaha electric blue paint that PJ1 sells is a lacquer paint. Not the best suited paint for off road bikes but you can clear it with a uerathane enamel to protect it. I had fairly decent luck spraying graphics on my radiator shroud and fuel tank.
I let the tank set empty with the cap off for atleast a week and scrubbed it real well with a scrub brush and Comet. Then I washed all plastic I was going to paint with mild soap and water with a scotch brite pad to make sure it was clean and to take off any gloss on the panels. Since I was only making a design I masked off the areas and then washed off the areas to be painted with Acetone. I was certain it was only going to flake off with time but was pleasantly wrong. It did however wear off from the inside of my knees like is was sanded off in a couple of spots.
Thanks for the info guys. I am only planning on painting my radiator shrouds blue since they are kinda scarred up and would match the rest of the scheme. I will coat them with the clear as suggested. I will let you know how it turns out. The only thing I am worried about is that since my bike was originally red/white ('86 yz250) and the guy I bought it from changed it to blue/white, I don't know what blue will match. I figured there was one "Yamaha Blue" but I was wrong. I will try the electric blue, since the others look purple and my bike is definately blue, just like the blue on most "Yamaha" stickers.
I will have to take a picture of my bike to show the color. Since it was changed over from the red/white scheme, I am sure he just used any available blue, so I might be down the wrong path. I will probably just try to color match it with a quality plastic paint. I will post a picture on Monday when I get back to work.