AK550 Fill to Gas Cap and Gas Seapage on Center Stand...?

[Luckyword]

When I fill my AK 550 with gas all the way to top, and top it off to the maximum, with just barely enough space for me to put the Gas Cap back on without any spillage...

...when I drive a half mile home and put it in my garage on its side kickstand....

...later that day or the next morning there's a small amount of gas seepage on the garage floor, and there's a smell of gasoline. I've had to put down a few rags to clean up the drips of gas.

What I've done to solve this issue is just keep the bike parked on its center kickstand after a fill-up and top-off.

Anyone else have that issue?

I'm assuming it's either leaking a tad right at the gas cap, or someone else down below.

I could experiment with adding less gas, but I haven't done that yet. I usually fill up about 3 gallons, and my biggest fill-up has been 3.402.

Related -- it seems if I have half a tank left and go for a ride, and it's been on the center stand, the fuel indicator seems more reliable. I've noticed if I have half a tank left before the ride, and it's parked on the side kickstand, the fuel sensor seems to be less accurate (at least, at the beginning of the ride).

[Neil955i]

I suspect you've answered your own question here Luckyword!  If you held the scooter upside down it'd probably leak a bit of fuel too!  Seriously,  the heat of the engine on the sidestand would likely be enough to cause expansion of the fuel in the tank to the extent that a little would seep out, either from the seal or even the breather hole.  Solution?  Either don't top off or use the centre stand like you are doing.

As an aside, a number of gas stations I used in Colorado, Arizona and New Mexico when I was over there in the 90's had signs up warning against "topping off".

[rjs987]

First, the fuel system is a sealed/pressured fuel system like a lot of bigger bikes and cars. The gas cap has a seal that will allow some gas to seep past if filled TOO full.

Second, never fill to the top of the neck of the tank or even close to that. That's what that bar is for that goes across at the bottom of the neck of the tank. That bar indicates FULL. I never fill up past that. I do fill up the tank when on the side stand. Since the fill opening is in the center line of the scooter it really shouldn't matter if the bike is straight up or leaned over a little. The only difference is the level is angled rather than level. When I fill up, I fill until half the fuel level is a little over and half is a little under that bar so that the center line of the fuel level front to back is even with that bar. That way, when I stand the bike straight up the fuel level is still right at the bar. I also have never had any seepage. But the rubber tray around the fill neck is designed to catch overflow and has a drain hose to drop any overflow down under the bike instead of on the engine. So what you have seen is normal considering that you over fill your tank (based on your description).

Due to the reason for those warnings on the pump about "topping off" I never put in more gas even in my cars than what it takes to automatically shut off the nozzle. The evap and fuel vapor systems will break if I do like I see a lot of people do... keep pulling that trigger even though it keeps shutting off every time they do that. You will loose fuel to seepage doing that and also in a car damage the vapor re-circulation system. That amounts to wasting fuel.

[NorWeWa]

The air vent for the gas tank is through the charcoal canister, EVAC system. If the venting to the gas tank gets clogged you may start having starting problems. Best to not top off the tank. The extra gas just gets pushed into the charcoal canister, which eventually will ruin it.

Art 

[Neil955i]

First, the fuel system is a sealed/pressured fuel system like a lot of bigger bikes and cars. The gas cap has a seal that will allow some gas to seep past if filled TOO full.

Second, never fill to the top of the neck of the tank or even close to that. That's what that bar is for that goes across at the bottom of the neck of the tank. That bar indicates FULL. I never fill up past that. I do fill up the tank when on the side stand. Since the fill opening is in the center line of the scooter it really shouldn't matter if the bike is straight up or leaned over a little. The only difference is the level is angled rather than level. When I fill up, I fill until half the fuel level is a little over and half is a little under that bar so that the center line of the fuel level front to back is even with that bar. That way, when I stand the bike straight up the fuel level is still right at the bar. I also have never had any seepage. But the rubber tray around the fill neck is designed to catch overflow and has a drain hose to drop any overflow down under the bike instead of on the engine. So what you have seen is normal considering that you over fill your tank (based on your description).

Due to the reason for those warnings on the pump about "topping off" I never put in more gas even in my cars than what it takes to automatically shut off the nozzle. The evap and fuel vapor systems will break if I do like I see a lot of people do... keep pulling that trigger even though it keeps shutting off every time they do that. You will loose fuel to seepage doing that and also in a car damage the vapor re-circulation system. That amounts to wasting fuel.

The air vent for the gas tank is through the charcoal canister, EVAC system. If the venting to the gas tank gets clogged you may start having starting problems. Best to not top off the tank. The extra gas just gets pushed into the charcoal canister, which eventually will ruin it.

Art

Well guys, far more technical explanations than my simplistic assessment (KISS principle in action!), but I think we all agree.  Far better not to over fill.

[NorWeWa]

It's my habit to fill the tank at the start of a ride, or during the ride, and not to fill at the end of a ride to have the scooter sit in the garage with a full tank.

Art 

[Stig / Major Tom]

Yep, Don't over-fill.
There is a whole song-and-dance for filling some Vespas to keep from splashing gas on your Moon Pies under the seat!
At a gas pump ----my Piaggio is a pain. You better not try to "fill" it! So.....I do it at home using a gas can and a flash light - and a key in the ignition to see if the bars are filled on the gauge. When they are - I quit.....since I'm heading out for coffee - not Clevland.

Stig