How can I prevent paint chipping around gas cap?

Yes, I'd be very careful using a funnel. The homemade milk jug jobbie worked fine the few times I did it that way, since the jug's opening was large enough to fit the nozzle thru & I could see the fuel level in the tank. But it was a nuisance, so I quit doing it that way. I also fill up to about the level indicated in the owner's manual & w the bike on the center stand.

You know I have had two tanks painted on my bikes. I am anal about details. Paint still comes off around the edges. There is something that autobody shops miss in putting in the paint I think because my friend got his painted by a professional and his didn't do that at all.
Gotta be some kind of hardener or maybe the tanks are baked or something but it's a PITA to spend that kind of money getting bike painted and find later the paint doesn't work like it should. The fumes come off the tank. So on a hot day you don't necessarily have to spill any gas on the side ever. None of my factory paint bikes have I had that problem with. Just the tanks I had painted.

I was thinking along the same lines as you sax. My 750 has the factory paint job and all it has is a little wrinkling around the filler neck. After 30 years and surviving my learning experience with motorcycles it should be way worse. Maybe the clear coat from the factory is different. Maybe one of the painters that know more about these things will chime in.

Quit spilling gas on the tank or filling it too close to the to. Gas gets hot expands and comes out the vent. Make sure the rubber cap gasket is good and keep a good coat of wax on it in case of spills. Rewax after any spills.

Well, I can say this, I have overtopped my original paint tank and had to wash off the gas a few times before yet I never experienced any problems, ever. None of my other bikes have I had these issues with either.
Gas is very corrosive to paint for sure but a week after I get my tank painted and it bubbles up is not acceptable as I never spilled on it or overfilled it. IMHO
The fumes on a hot day are enough for that reaction to happen. I always sit my bike on its side when I fill the tank and at least two inches from the top so I don't believe on my part that I am doing anything wrong. I just think the paint or additives are not quality enough. Also the painters like to paint the lip. I think therein lays the problem. On my stock tank the paint on the neck is like over spray, a very thin coat. On my painted tanks that bubbled both were painted.
Question is would that be easily fixed or does it have to be completely repainted.

I'm pretty sure any early to mid 70's factory candy paint is nitrocellulose lacquer which all modern basecoat/clearcoat paint is supposed to be so much more durable!? Someone on here must know something about the factory painting process.

Well it sounds like the answer to my original question is there isn't much I can do to keep the paint from chipping and peeling around the filler hole. Sounds like it's a fairly common problem with non factory paint jobs.

Best suggestion I've heard so far is to remove the paint from the neck and hole and put a good coat of wax on the tank.

Paint from the mid to late 70's was mostly acrylic lacquer and that is what the Kawasaki Candytone paint acts like. The new urethane paints are more durable when done right, but if recommended dry times between coats are not followed, or products are mis-matched, or tank was not cleaned or prepped correctly, I can see the clear wrinkling when soaked with gas due to a poor chemical bond between base coat and clear, or original paint and primer. Also paint manufacturers say to let paint cure for 3 months before waxing, so if you gas up a one week old paint job you are asking for trouble. It takes a paint job a year to cure before it gets good and hard.

Paintworkz, thanks for some straight answers. That clears up a lot of confusion.

PaintWorkz wrote:

Paint from the mid to late 70's was mostly acrylic lacquer and that is what the Kawasaki Candytone paint acts like. The new urethane paints are more durable when done right, but if recommended dry times between coats are not followed, or products are mis-matched, or tank was not cleaned or prepped correctly, I can see the clear wrinkling when soaked with gas due to a poor chemical bond between base coat and clear, or original paint and primer. Also paint manufacturers say to let paint cure for 3 months before waxing, so if you gas up a one week old paint job you are asking for trouble. It takes a paint job a year to cure before it gets good and hard.

Nice! Thanks for the feedback. I'm sure I need to have you guys give me a quote for my 80 project I am doing. PM me with your ideas for a nice bling paint job. You have my vote. I like black black and deep black.
This guy that painted my bike never even mentioned to me about that happening. I guess when you paint cars for a living those aren't issues that come up.