TOPIC:

I have an 82 LTD 1000 with an aftermarket gas cap put on by the PO. I noticed that when the tank is over half full, gas slowly leaks out the tank and down the left side when the bike sits on its center stand. The gas cap looks good and the gasket looks good. There is a little bit of paint on the tank where it meets the gasket but it looks smooth. Could this be causing the problem?

thanks

I don't have the same bike but had a similar problem. Does you gas cap fasten on with two screws if so make sure the orings are there they are located around the screws you will see a seat for them. If there is a place for them and even if they are there replace them with new ones.

Could it be a venting problem somehow?

Although the following link dealt with curing gas cap leak while on side stand, thought it might possibly help.


kzrider.com/component/option,com_joomlab...id,6/id,95932/#95932

Great ideas - I went out last night and saw the two screws and wondered if there was an oring or something leaking..... now I have some good ideas.

Now... how to work on this thing? I think I should drain the tank completely and also get the fumes out before working on it - right?

The cap on my ST tank was leaking. The gas cap hinges and is retained by two 5mm screws. To seal when closed, it press fits a rubber round gasket against the round filler neck. The clasp part is what gives the seal some pressure. If the orings are shot, they are too compressed to allow the clasp to give enough pressure and there is a poor seal. To fix the problem, at 2bskor's suggestion, I replaced the orings around the two 5mm mount screws. I also recovered the rubber gasket with new rubber to build it up a bit. The leaking stopped... when you shut the clasp on the tank, it now fits a bit tighter. You can do this stuff with the tank full of gas... it makes no difference; you don't have to remove the tank.

You said you had an aftermarket gas cap? What does it look like? It should be vented otherwise it will create a vacuum lock and gas won't flow to the carbs. Some cheapo aftermarket caps may actually vent too well where gas can get through the venting.

I went ahead and drained the tank. I didn't go to the trouble of taking off the fuel valve... though I was remembering how an empty gas tank can be more dangerous (explosive) than a full one. But I digress...

I took off my aftermarket gas cap (it was on the bike but I think jcwhitney or denniskirk sells them). There were two 5mm screws and NO o-rings. I went to NAPA and got two o-rings and put them in place with some gasket sealer and also sealed the screw threads then put it together.

I gently sanded the filler neck of the tank to remove any paint on the mating surfaces where the rubber gasket goes on the tank.

I think this will solve the problem. I think there was gas up the screws and under the cap, then when it was parked it would run down the side of the tank. Just a little, enough to leave a streak on my tank.

thanks for all the help!

I think the cap on a J bike is the same as on my ST. I have a J tank sitting on one of my shelves and it is the same. The point is to make the clasp grab tighter. If you have a cap that mounts with the two phillips 5mm screws, it should be a stock cap. Is it rectangular with a round seal on the underside that just seals flush against the round fuel opening? Does it have a key slot where the key slot is universal? That would be an OEM cap I think.

WG, you have described my gas cap perfectly. I thought the universal key type lock was aftermarket. A small flat blade screwdriver works in a pinch.

I think mine was leaking from both the cap itself and also the screw holes. Hopefully I have resolved this for both of them - I will know in the morning.

Happy New Year, and Blessings

David