Pressure in the gas tank

Is this normal, everytime I open the gas cap, it seems a little bit of pressure has built up, I can hear air escape (when opened). The tank is a little less then half filled, note I haven't driven the bike yet, I just turn it on in my garage. Just wondering this happens to everyone. I was thinking of drilling a hole in the gas cap and running a hose towards the forks, like this picture.

I've never had a problem with gas pressure build up on my CB350.

Maybe your the vent in your gas cap is plugged with something.
It isnt uncommon to hear pressure releasing when you open the cap, but it should be minimal if anything..

i'd leave it alone unless there's some actual driveability problem.

i'd be afraid of putting a hole in the gas cap just in case of an accident/fuel spill. (i'm wary of fiberglas tanks for the same reason.)

if the gas cap is plugged, i'd be more worried about fuel starvation out on the road because of a vacuum in the tank.

Where do I find this plug on the cap? I have the same cap like in the picture except it doesn't have the hole. I did replace the seal on the cap with a rubber one I bought at the hardware store. The old one would leak gas, and now it's pretty tight.

if your gas cap's like mine, if you look at the underside of the gas cap, you'll probably see a small hole (say 1/16") and 3 small screws. if you undo the screws and lift off the cap with the rubber seal, you'll see a paper gasket. and if you lift off the paper gasket, you'll see a second 1/16th" hole directly in line with the first one.....the 2 holes are just separated by the paper gasket which i assume is porous enough to let air bleed thru it.

maybe there's just some rust plugging the holes? but like i said, i wouldn't worry about it unless there's some driveabilty problem.

Thanks, I am encountering problems, the bike seems sluggish when I shfit gears, it seems it want to die out. I checked my cap, but there is not screws. Here is pic of what I have.

http://www.classiccycleparts.com/aduploads/75f53900-7fcf-4802-bfff-70b48ca7ac60.jpg

I try to clean it out as much as possible.

Cafe_to_go said:

the bike seems sluggish when I shfit gears, it seems it want to die out.

Click to expand...

another option is use a clear heavy plastic bag (like milk comes in) as a gas cap, and use a strong elastic band to secure it in place. then prick a hole in it, and take the bike for a run. if the stumbling disappears, then it seems the gas cap vent is plugged.

Pressure in the tank ???

I had a very strange experience this winter with a 350 ice bike. The tank was quite bad and actually had a couple of small holes.

Whenever I started it gas would spray out from the holes. Literally shooting out a few feet in a very thin stream. It would stop when the bike was shut off. I can think of no logical reason for this. If anything I would think the pressure inside drops as the fuel flows into the bowls.

Anyone got a theory?