Fuel penetrating under the tank paint

[ukilme]

Bring the tank to the guy and ask him how he would fix it. He may just do it for ya.

Filler necks are tricky to do if you have not done them often. From what I have seen and heard, it is actually the vapours getting under either the paint/clear and causing the damage.

There are several ways to deal with this but sealing is usually best.

[nvr2old]

You're absolutely correct. Trying to seal it with more clear will only leave another, even fresher, paint line for the vapors to penetrate. It needs to be sealed with a product that is gas resistant.

[GSX750ES junky]

Thank you guys for all the clever advises.
The tank was taken to a paint shop by the guy who sold me the bike a few years ago. I'll contact him tomorrow to track the painter.
I agree that a complete paint job will be the perfect solution but I still need to check if it's the best value for money considering the fact that 2 inches from the cap the paint cannot be removed with a screw driver.
I'm rebuilding this bike to display standards and money is running out.
If the painter can guarantee a local fix I'll go for it. Nevertheless, this time I'll make sure the painter provides a professional gas resistant sealing solution where the paint meets the gas hole.
The rubber seal, buy the way looks good. It wouldn't mind pampering with a high quality silicone grease which I have but it looks good.
I'll keep you updated in the next days.

[rustybronco]

It needs to be sealed with a product that is gas resistant.

nvr2old,

Thanks for the insight. when I finally get around to painting the Skunks tank, I WOULD have made that same mistake. not now because of you!

[chuck hahn]

I still think the number 1 thing is to be absolutely sure the cap gasket is sealing COMPLETELY

[chuck hahn]

I would also suggest a little emery cloth on the sealing edge of the filler neck as well to insure its smooth and rust free so theres a positve seal all the way around.

[GSX750ES junky]

chuck hahn,
I re-checked the cap and its rubber seal is good as new. The tank is completely sealed. Also coated the rubber with silicon grease which I have and is known to make rubber applications last forever.
I talked to the seller and he confirmed that the tank is sealed but mentioned that the painter was neither a Leonardo da Vinci and Botticelli descendant nor a motorcyclist which can explain the problem I'm facing.
In my area there's a painter that worked 3 years in Miami on high $ choppers which amazed me with some of his works.
I'll drop the tank at his shop tomorrow and update when it's done.

[chuck hahn]

The rubber may be good as new but does it seal properly? Since its gonna be worked on any ways, i would take it and fill it with enough gas to flip the tank on its sides to see if theres any weepage anywheres.. Do this before you take it to the new painters. That way you can be 100% sure the gasket is doing its job. Better to find out on a damaged tank first!!! OH and have you looked at the condition of the oring at the bottom of the lock cylinder? Take the black plastic latch cover off and youll see it there. That can also let fuel seep out the cap

[Adler]

The rubber may be good as new but does it seal properly? Since its gonna be worked on any ways, i would take it and fill it with enough gas to flip the tank on its sides to see if theres any weepage anywheres.. Do this before you take it to the new painters. That way you can be 100% sure the gasket is doing its job. Better to find out on a damaged tank first!!! OH and have you looked at the condition of the oring at the bottom of the lock cylinder? Take the black plastic latch cover off and youll see it there. That can also let fuel seep out the cap

Interesting point about that o-ring. mine is pretty gone. Anyone have any ideas on replacing it?

[chuck hahn]

regular oring from any hardwrae will do. Take the old one or even the cap body with you to fit one. I should add a footnote here. I should add a footnote here:: If the oring leaks youll n otice it around the lock cylinder first. Ask me how i know!!

[tkent02]

You could also quit overfilling the tank when it's going to sit.

[chuck hahn]

I filled it at the start of my buddies dirt road. Then proceeded down said rough road to his house. Gas sloshed arond and next thing i know it has seeped out the lock cylinder hole and the tank was wet and full of splatter spots. Thats how i discovered the dreaded O ring.

[spchips]

Maybe they used rattle primer?

[GSX750ES junky]

chuck hahn,

chuck hahn,
I turned the tank upside down and It leaks like an open tap from the side of the cap. Not from the key hole.
Are you sure an upside down tank is not suppose to leak ?
I don't understand how a new Suzuki original cap with a perfect rubber seal is leaking ?

[chuck hahn]

It should seal against all reasonable scenarios..Just think of all the leaning angles when riding. If the bike is leaned over to the left or right then gas is gonna slop up the filler neck..right?? The seal has to seal or gas will seep out and F up the tank again..right?? see where i am going here? As your going from one lean angle to another like on a twisty road..gas sloshes in all dirction in the tank right?? Dry it all off and slosh it around just like if your riding it. its a vented cap. Gas is coming out the vent..I didnt mean to litterally flip it upside down..shake the crap out of it like i described in a riding type situation.