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Old 12-09-2011, 03:23 AM
kaizer_soze kaizer_soze is offline
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Join Date: Dec 2011
Location: TX
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Default Re: Leaky gas cap?

I quick fix that worked well for me was to wrap the top of the lip of the opening in the tank with plumbers tape (not really tape, white, adheres to itself and fits to any shape). I had to cover the lip with at least 10 layers of the tape, but now the cap sits tightly and there is zero leakage even with a full tank.
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Old 12-09-2011, 07:16 AM
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Allen_Wrench Allen_Wrench is offline
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Location: Indianapolis
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Default Re: Leaky gas cap?

Originally Posted by GearNut View Post
Leather makes for a decent gas cap gasket material. Inner tube rubber will eventually swell up to almost twice it's original size.

Edit: Sheet cork, available in hobby stores, also works very well.
Inner tube rubber also dissolves in petroleum products. I have personally done this to prove a point. Leather and cork aren't too bad. But when I built my tank out of a softball bat, I realized I would need to make my own vented gas cap.

I used a large, threaded brass fitting for my bung which had a companion threaded collar. I made a brass disk to close the end of the collar and turn it into a cap. I used a large ball bearing and a hammer to dish the disk a bit. I then drilled a hole for a rivet in the center and a vent hole just off-center, in the disk. I made a Nitril rubber washer to fit inside the disk.

Nitril is ideal because it is NOT dissolved by gasoline. First I soldered the disk into place at the open end of the collar. Then I riveted the washer to the inside of my cap with a small brass washer in between. Air comes in through the vent hole and can get past the Nitril washer, but fumes can't blow out through there - the washer seals against the disk. It is designed, however, to vent from inside if you blow VERY,VERY hard. This is a stopgap against pressure buildup.

"There is nothing wrong with wanting a motorbike that is an extension of your personal taste and fashion sense; if you must ride somewhere, I say do it with style!"

Last edited by Allen_Wrench; 12-09-2011 at 07:23 AM.
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Old 12-09-2011, 08:18 AM
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thegnu thegnu is offline
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Join Date: Sep 2011
Location: freedom pa
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Default Re: Leaky gas cap?

Originally Posted by bairdco View Post
to solve the problem, take your cap off and set in on a hard concrete or metal surface.

next, take a BFHammer and hit it as many times as you want. (note: cap must be hit as hard as possible.) (note 2: cap will try to retaliate by bouncing up and hitting you in the face. wear proper protection.)

step three. dispose of cap properly.

that will solve the problem of the leaky gas cap, but opens up another problem. "where do i find a new gas cap?"
Heres a guy who does NOT fool around , Ima fan of the get a bigger hammer alignment system as well .
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Old 12-09-2011, 12:00 PM
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Nashville Kat Nashville Kat is offline
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Join Date: Apr 2009
Location: Jacksonville, Florida
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Default Re: Leaky gas cap?

A thin piece of nylon material like the top of a sherbert or cottage cheese contaner is great and gasoline proof- you can put one or more UNDERNEATH the normal rubber gasket

works every time!
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Old 12-09-2011, 12:11 PM
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CroMagnum CroMagnum is offline
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Join Date: Sep 2011
Location: Los Angeles
Posts: 138
Default Re: Leaky gas cap?

Back in the 1970s I used to use a "Slopper Stopper" on my dirt bikes. Basically it was just a big foam rubber donut that stretched over the gas cap. It still let the tank vent, but when gas dribbled past the cap the foam would soak it up.

Get some open cell foam and cut it in a circle a couple of inches bigger than your gas cap. Then cut a hole in the middle just about the size of the filler neck. Screw on your gas cap, stretch it over the cap and you're good to go!
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