Where does the Gas go??

[Ulshy55]

So when I fill up my Kat's gas tank I usuall fill it to the top, then let it settle and put a little more in. Now i've been noticing this happening but just decided to post now. Once the tank is full you can pump a little more gas into the tank till it is near the very top, and then it drains back down to a little below the top, and you can put more in. You can do this multiple times and the gas level keeps draining down after filling it to hte very top. So where is the gas going?? Is it draining into the reserve tank or draining out of the tank somewhere? I don't notice any gas leaking out anywhere, and i know there is no leak in my tank(or else it would leak all the time), so WHERE DOES IT GO?

[Sundowner]

Basic Physics really. As you fill the tank with Gas, the liquid pushs the Fumes andair out of the tank (thru the Filler Neck) as it happens, the Liquid level falls a little and you can add more fuel.

[Ulshy55]

The filler neck?? I thought about that, but i didn't see any bubbles coming out the top.

[whitecl0ver]

I never really thought about it that hard......

[Brosh187]

Rofl

[Fox Fader]

It's all about fumes.

That's why when fill a cage it's advisable to pump slowly. Creates less fumes.

[thetable]

The best way I can explain it is with a picture:


The blue area is fuel, the gray is air. The grey area vents and the fuel is able to slowly drop down into the gray area until the fuel is level across the entire tank including the filler neck.

[StevieB]

You can finagle more gas into the tank by "burping" it, or tilting the bike back and forth, but you really shouldn't. Gasses are compressible, liquids are not. That air space is there so the fuel does not overflow the tank if the temperture rises before you have used enough fuel to produce more air space- something that can easily happen: Most of us fuel up at the beginning of the day. It's a good idea, too- lower tempatures mean the gas is slightly more dense so you effectively get a little more, and less fumes are released into the atmosphere- which means a little more gas for you, a little less pollution for Mother Earth. They, we ride a short distance- to work, or to breakfast, and park the bike, usually in the sun. Ol' Sol does that thing he does best, and the temp. rises and your fuel expands. Best case: you come back to a bike that is standing in a mysterious puddle of fuel, and spend the next hour looking for the leak- which is now gone because enough fuel has vented out to allow the tank air space to work as designed. Worse (although rare) is the bike won't start or run, because the completly full tank now has a vacuum in it which does not allow the fuel to flow- like filling a straw up with water and holding your finger over the top end. And the WORST case scenario-

Kat flambe'!

[Black_peter]

I agree with Stevie..

[chinto]

I agree with Stevie..

I agree to a certain extent. The only thing I disagree with is this:

You can finagle more gas into the tank by "burping" it, or tilting the bike back and forth, but you really shouldn't.

I would just add that you shouldn't all of the of the time.

An exception to this would be on a long trip when you will be using most or all of the fuel immediately after filling. On trips when i am running tank to tank, I squeeze in every last drop I can.

[BLACKDEATH]

An exception to this would be on a long trip when you will be using most or all of the fuel immediately after filling. On trips when i am running tank to tank, I squeeze in every last drop I can.

Thats exactly what i do. When on a long trip i squeeze every ounce in there i can. Because in 20 minuts I will be 1gl less anyways.

[jgust25]

They did the "denser gas in the cooler mornings" thing on mythbusters, and the density/quantity differential is negligible. True, but not really much different.

[yellow_kitty_kat]

I was going to go with the "it goes out of the exhaust, silly!" theory... But now that I think about it, it is a cool little mystery.

And now it is solved.

[jndodd]

I do too. When travelling I fill it to the schnozzle!!

[Zepp]

I have been asking myself that on the ZX-14, where does all the gas go?

It doesn't do nearly as good as the Kat does, but it is a lot more fun using it.