I'm getting some bubbling around gas caps . I put some clear nail polish on to seal it until I had time to fix properly. I have pop up caps which are notorious for this so I need to replace. My plan is to cut back paint past the bubbles ( about 3/16 inch) And seal with jb weld. I'm going to replace the gas caps and was thinking Kurakyn flush mount vented cap (ky8309) . If these cover enough of the area around the gas cap area I wont need to do a really neat job. I need a cap with a lip big enough to hide my hack job. Anyone know how far past the filler hole the bottom piece covers? Another thing is would if pay to JB weld the ring directly to the tank for a vapor proof seal? I know I wont get it off but if done right I would need to. Would this block venting?Anyone have a better idea ? Looking to do this myself if possible and not pay a painter. Thanks

 

sound like it would work but why the JB weld? why not remove the bubble section. repaint that with some auto touch up, and then put the new cap on that will cover that area

 

Paint fumes under the paint is why it peeled in the first place.

 

Bump.. anyone know how much of a lip the trim ring has over the paint. Dont want to buy it if it wont work. Anyone have a kurykan ky 8309 they can measure??

 

bumpp

 

Once gasoline fume works itself under the paint, nothing that you apply on the top will stop it from moving and lifting your paint further. Applying nail polish or paint to the edge of the filler neck, will not help, because no nail polish can resist fuel vapor. JB weld holds for a few months, but will also allow fuel to get under it and pass through. We have tried all the tricks imaginable. Paint savers and custom gas caps that sit on top of the paint, actually contribute to lifting and destroying paint jobs, simply because they create a chamber and space around the filler neck which allows gasoline fumes to sock and soften the edge of any paint job, instead of evaporating!

Painters are usually blamed for this very common problem and many painters actually take the blame, because they think they have done something wrong, but paint lifting around the gas tank filler neck is almost never the painter's fault. No liquid automotive paint on this planet is fuel resistant, even the best automotive paint brands are only fuel repellent, when exposed to fuel for longer periods of time; they will all sustain damage or lift.

Colormania solved this very common problem in early 90s by simply trimming back the paint away from the pressure & sealing point of gas cap gasket. If any fuel vapor gets through the gas cap gasket, it will evaporate, before it has a chance to soften our paint job!

If this was my bike; I would repair the paint and use a factory gas cap or any custom flush mount that does not sit on top of the paint.

 

Thanks for the reply. I'm going to trim back the paint to where its still good then seal with jb weld and also jb weld the trim ring directly to the tank. This should give me a welded seal from the filler out to about 1/2 inch. If the JB weld holds no fumes should be able to get thru and fumes would need to travel up over the trim ring to get to the paint. Look at the cap kurakyn 8309 and tell me what you think. In my head it works. Once again thanks

 

The problem I've found with these caps is the vent is on the wrong side of the bike so the vented cap leaks when the tank is full and the bike is on the kick stand. They almost ruined my Titan tank. I made sure the new caps that the vent was on the right side.

 

make sure that there is no paint inside of the bung.. i got in this argument when my buddy painted my shovelhead.. we had several moto-guzzis come back under warranty at a shop i wrenched at. if the paint is below the cap seal, it acts just like a wick.. fuel will bleed up and ruin the paint.. a bad cap would have the same effect with fumes. once the paint has fuel in it, the only fix is to remove the contaminated paint.. trimming the paint back and using a wider cap would probably work.. moto-guzzi had us scrapping the paint under the cap with a razor blade on every bike that came in built between two dates.. it happened to be every bike on our show floor

 

This happened to my 09 Night Train a few months after I bought it. HD payed to have the tank repainted and it has been fine ever since.