Gs1100G Belching

[rgierer]

I have a 1982 GS1100G that will literally belch gas. I have taken to filling the tank 2/3 of the way in order to keep it from forcing gas out of the tank (with the cap on). The phenomana is so pronounced that I believe it to be responsible for the damage to the clear coat on my tank and side panels.

The PO had the tank lined by a radiator shop and I am assuming that during this process they blocked a vent. In the near future I am going to pull the tank and rebuild the petcock, at this time I want to see if I can identify anything that may be blocked.

I can not overstate the oddness of this behavior. It may belch gas while I am at the pump and have just filled up. It may belch gas with the cap on with the bike on the center stand.

I did a search and found people who have just learned to live with this peculiarity but no real guidance on a remedy.

While it may be more pronounced during hot weather it is not limited to the summer months or extreme temps of any kind.

Any help would be appreciated

[tkent02]

Make another vent hole...

Not sure about your exact model but on the older GSes, there is a collar inside the top of the tank around the filler, it comes with a small vent hole near the top.maybe about 1/16" diameter hole. I have always enlarged the hole to about 1/4" so I can fill the tank faster. It sounds like yours got blocked completely. Gas expands, air in the tank expands, the only way out is through the gas cap. The little vent hole lets air go into the collar and out the vented cap instead of gas. Without the vent it has to push gasoline out the gas cap. So make a big vent hole in the side of that collar as high a you can get it and you should be set.

[Jethro]

Usually it happens much more in the summer. Gasoline sees huge changes in density and volume with changes in temperature. In the summer it is common to have cold gas from 15 feet below the ground come up to ground level with a 50-70 degree temerature change. Gasoline also responds to temerature much quicker than say, water becasue of it's much, much lower density. Within a few moments a tank of cold gas that is introduced to a very warm tank expands a huge amount.

I always put the filler nozzle about an inch below the filler neck of the tank and when the pump clicks off, that's it. Even then I have seen some expansion.

As far as vents, the ony ones your tank has is in the filler neck, and in the cap itself. The only other way out for gas or vapor is through the petcock. Or the fuel gauge sending unit if the gasket fails.

[rustybronco]

I have a 1982 gs850g i regularly fill it to just below the lower part if the neck on the side stand and NO belching at all, the vent is in the cap did they coat it also when sealing the tank? how is the rubber gasket on the fill cap?
the clear on the top of my tank is coming off but I believe it's because of the old clears they used, they would delaminate from the base coat.

[rgierer]

Thank you for the responses I will be checking the vent tube in the next few minutes.

Again this is WAY outside of the normal range. I am hoping to find this tube completely blocked so I have some hope of resolving the issue.

[rgierer]

I went downstairs and took a look inside the tank. If there was a vent hole in the collor there is NONE now. I will check one of my other bikes and see what these holes look like and go at it with a drill if I have no other option. thank you

RG

[Boondocks]

The vent must be working well on mine. I fill the tank with as much gas as I can put in the tank without overflowing. I've never had any "belching" problems or problems with gas expansion. I fill the tank to the top with the bike leveled between my feet, and after replacing the cap and leaning the bike on the sidestand it still doesn't leak or belch.

[rustybronco]

I went downstairs and took a look inside the tank. If there was a vent hole in the collor there is NONE now. I will check one of my other bikes and see what these holes look like and go at it with a drill if I have no other option. thank you
RG

I tried to look this morning at the filler neck in the tank to be sure but I didn't get the chance, i'm almost 100% positive there is no hole in the neck. let the tank run low in fuel in fuel and take a coat hanger and bend it and go inside and see if there is something wrong inside such as a flap of sealer capturing a pocket of air or try filling the tank 3/4-7/8ths full of fuel and rock the bike side to side looking for a big bubble coming up, a small mirror is an option also.
sumtin wong...

[rgierer]

I appreciate the exploration. I will check out another bike I have to look for a hole in the collar as well. I will check out the gas cap but I really think that is a red herring as it will do this with the cap off of the bike as well as on.

[rgierer]

please be apprised

after a bit of exploring and comparing to other tanks I did find where the vent hole was in my tank ( the one on the collar). It was fully and completely blocked by the liner. After a bit if ardous digging (I was hesitant to put a drill on it) I was able to ID the spot, poke a hole and drive a punch through it and now have a proper vent hole. I am in hopes that this will remedy the mindless belching.