No Vent in tank

[Ickaruz]

Ok, after using all of your kowledge I have finally determined that my tank don't vent. It is a 85 gs 700 by the way. So, if I detach the fuel ine and run a separate into a container, turn the petcock to free flow the gas starts to come out at a goos clip, however that soon changes to a trickle. Then I pop the gas cap and the flow returns. So now I need to know how my tank is supposed to vent and did I seal something when I treated/ coated the tank for rust. I took some shots and osted them in the album. If I blow throught the nipple under the tank air comes out of the hole underneath the cap. I think this is a drain only but I really don't know jack about the workings of a gas tank. Please check out the picks and let me know what you think.

http://www.thegsresources.com/_forum/album.php?albumid=104

[Billy Ricks]

It's mostly the vent in the gas cap that is clogged. The port in the tank under the cap is just for overflow and to let water out of the cavity when it rains or you wash the bike.

[Ickaruz]

Cap

That makes complete sense to me. But the cap is new. Maybe they sent me a bum cap?

[Smokinapankake]

Did you use your cap to plug the filler hole when you treated your tank? I did the same thing with my GPz and had the exact same problem you're having. Took me months to figure it out (this was before I joned the GSR).

Inspect the cap, see if there are any holes or passageways that appear to be clogged. Same for the tank itself.

My 84 Kat has the same cap; I couldn't see any way for it to vent. Check all the little holes in the tank where the filler cap goes - they may be plugged somewhere. Sorry I'm not more helpful, keep at it and you'll get it figured out.

[Smokinapankake]

So I looked at my cap, there is a screw on the bottom of the cap that I presume holds everything together. Try pulling that screw out and having a look at what's inside. These caps aren't that complicated so I'm sure you'll have no problems with it. If you used the cap to plug the filler hole when you treated the tank, I would bet some sealer got inside the cap somehow, and is plugging whatever mechanism it uses to vent. I think the sealer can be cleaned out with acetone, but check the instructions.

[Ickaruz]

Still no clue

Ok, I dissassembled the whole cap. I didn't use it to plug the tank when I sealed it and is brand new. I don't see how this cap vents though seeing as it has one lower rubber seal and one upper. What i did use when I sealed the tank was lots of duct Tape slapped on the outside. That is why I am so concerned that maybe I plugged something below the immediate opening. Just to be sure can someone just take a peak inside their own tank to see if there are any little holes besides the one immediately visible, which is used for a drain. I'll post a picture of the dissassembled cap if anyone is curious in a sec.

[Ickaruz]

Pics up of cap

http://www.thegsresources.com/_forum/album.php?albumid=104

Evrything is spotless but if you notice the two rubber gaskets- they do a great job of sealing the inside mating surface and the outside.

[Bill Lloyd]

Vent

I don't know what's up with YOUR bike, but I had a mechanic near here coat the inside of MY bikes' gas tanks and on each bike he "forgot" to make sure that the little holes in that "tube" just below the tank cap didn't get filled up and coated.... The result is that if I fill the tank after a ride -- that is, when the engine is hot and thus the gas gets quite warm -- the gas overflows onto the tank. The first time this happened I wasn't there, and the gas ruined the decaling on the tank. And now it's virtually impossible to FIND the little holes so as to prick them open....

-- Bill

[Ickaruz]

Wow!

That was what I was suspecting and waiting to here, however, I'm not happy to hear that. So am I SOL on ever venting my tank? I should have bought a tank from the salvage yard from the get-go but they wanted 250. Is it possible at all to make new openings and do you have any idea where abouts they are?

[Smokinapankake]

Hey Ickaruz,

I looked at my tank and I also have a drain nipple on the bottom. However, unlike the pictures I see of yours, I have three holes. One to the drain nipple (I assume), two on the lower, inside edge.
Check the link here: http://i270.photobucket.com/albums/j...e/IMG_6529.jpg

The hole on the outer edge is at approx. 10 o' clock. The hole on the inside, deeper, is at 12 o' clock, with an identical hole at 6 o' clock.
The 12 and 6 holes are just that, holes that lead nowhere. I suspect to drain gas back into the tank.

Any more than that and I'm out of ideas.
But - these are simple machines. This can't be that difficult. The tank HAS to vent somewhere. You should not have to replace the tank if it is structurally sound. Something got plugged somewhere - you'll just have to find it. What brand sealer did you use?

[Agemax]

if all else fails, rather than buying a new tank, you can buy after market tank breathers like they fit on race bikes. would look quite trick IMO. thinking about one myself, just for the looks.

[BentRod]

ok, as best I can tell from what I read here, evidence that the cap is not venting is that when you try to drain the tank of gas, it only comes out in a trickle.... perhaps suspicous, but not condeming

try one more test on your cap. put your mouth on any opening on the top, including wher you put your key in, and blow hard. If even the smallest amount of air can get through then your tank is sufficiently vented. The greatest air pressure a human could produce will be well below the pressure at which compressed petrol vapours would become dangerous. (not that they arn't already, but within a proper container this danger is minimized). Also, compressed vapours are not going to be created at such a rate that they cannot be evacuated quickly enough.

[Ickaruz]

Drilled em

I found where the hole used to me via curling my finger inside the tank and feeling little stalagtites. Driled em out and put everything back together. Thanks Smokinapankake for the pic, it was helpful. I appreciate all the advice and hopefully I have good news for you all tomorrow based on my ride today. Thanks again!

[Smokinapankake]

Sweet. Keep us posted.

[Ickaruz]

Woot woot!

Drilled out 2 holes below gas cap and bike now stays running! Thats the good news. It starts a little funny now though. I have to crank the idle screw a few turns to get it started and to idle. After a minute it idles smooth and the the tach bumps up. Then I crank the idle down again and it runs great. After it is warmed up I don't seem to have to do this again. Any ideas? Also the oil seal on one of my dampener is leaking. O, and I dropped the bike in the garage and smashed a mirror. But none of these things can break my spirit now! Thanks for all of you persevearence!