What does NOT work painting gas tank

[Mike R]

Hi--
I thought I would share somthing I did the a couple weeks ago -that failed.

I wanted to paint the plastic on my dirt bike--- So while at the paint store they had a gallon of duplicolor "especially for plastic" laquer thinned primer.

I put on two coats--over 220 scratches --let it dry in the sun a few days--

then used some PPG DBC (using laquer thinner instead of the correct reducer) and cleared it with some Upol clear.


All of the plastic looks great except the tank--which pealed off---right at the gasoline level--after about 3 days. The top plastic that has not touched fuel was fine.


--Most of you probably knew that would happen----haha---at least I only wasted a couple of hours and some scraps.

I am interested in opinions---can a plastic gas tank be painted if I had used 2k primer--or maybe had hardened base??

Or is all paint over plastic going to fail--when there is gasoline on the other side?/

All the other plastic still looks great --even after some off road crashes-

[Robert]

If you had posted what you were doing to this board, before you started, if anyone knew that was going to be a problem would have let you know. Since it's a dirt bike, is it premix that's been on the tank?

Obviously you're going to have to get the paint that's on there now off and figure out some way to make paint stick to an oily surface. I don't know how you're going to do that but there are probably people on this board who do.

Good luck and welcome to the board.
Robert

[Phil V]

If the bike is a 4-stroke then a good cleaning with some adhesion promoter sprayed on then a light coat of epoxy primer followed by your color coat should do the trick.

If the bike is 2-stroke with gas/oil premix then you SOL when it comes to getting paint to stick to that gas tank. I have had MANY motorcycles over the years (have 4 right now) and I tried several different things to get paint to stick to a 2-stroke premix gas tank and never came close to anything working. Had an old Bultaco Alpena 350 at one point which was a fiberglass tank with gas/oil premix and the paint bubbled on that one too. I washed the fiberglass tank several different ways inside and out. sprayed epoxy primer on the outside and used gas tank liner Kreem on the inside. It still bubbled because the fiberglass is relatively poros and over a period of time the oil from the premix saturated the fiberglass tank. Picture taking a rag and dipping it in oil. Squeeze out some of the oil and then try and get paint to stick to that oily rag, which of course isn't going to work. Its basically the same scenario with fiberglass tanks and the same with plastic (PVC) dirt bike tanks. Even just the gas alone from a 4-stroke bike will saturate into the Plastic. Thats why some gas tanks when new are white will turn to a pale yellow after a couple years. NO way to get those tanks white again.