Kymco AK 550 fuel capacity

[rjs987]

There has been some debate about how many gallons/Liters the tank is on the AK 550. Prior to 2021, and prior to the Euro 5 models, the tank is reported to be 3.9 gal/15 L.

Mine is a 2022 AK 550. The debate partly stems from the changes to the Euro 5 models which have a 3.25 gal/12.3 L tank. And now the AK 550 ST for Europe is reported to have a very slightly larger tank, maybe 12.4 L (almost 3.3 gal).

So I decided to attempt to measure the volume of the tank on my AK 550. The manual says 3.9 gal/15 L. But due to controversy I figured the best way is the siphon the tank empty, or as empty as possible, and measure how much gas I put back in for a full tank.

I have a 1/4 inch vinyl tube that I attached a small wooden dowel to the last 8 inches to keep it straight. The tank on the AK is almost a cube with rounded corners, so I was expecting to get almost all the gas out I was able to get the siphon running without sucking the end. (the tube fit snug into a funnel I was using so I primed the tube using that). I have an extra 5 gal gas can so that's where the gas went into, but I only really had less than 2 gallons in the tank to start with.

When the siphon stopped I used my flashlight to find that there was still some gas left. After feeling around the bottom of the tank with my tube and dowel setup I found that there is a slight drop in the tank bottom just under the fuel pump. I was unable to get the siphon going again to get that gas out. I am guessing there was somewhere around .75 to 1 L of gas left in that well under the pump that I wasn't able to get out, maybe a little more. So I started to measure and refill the tank.

I ended up putting 3.63/13.75 L of gas back into the tank. I was using the Liters measurements on the 2 Liter bucket I had with 250 mL markings on the side. With the gas that I could not remove I would guess that my tank is indeed what the manual spec says it is... 3.9 gal/15 L. I put the AK on the side stand before I filled it all the way since that is how I always have it to fill the tank at the station.

Since I was not able to get all the gas out I did run the engine for a while to see if I could burn off what remained but didn't want to do that for very long so as not to damage the fuel pump. I intend to try this again but next time I want to get a siphon bulb with a one-way valve to get more of the gas out.

[rjs987]

Been wanting to be more certain of the tank capacity on my AK 550 since earlier this year when there was discussion that the tank might not have the capacity advertised. See above for the first time I drained the tank as much as I could and measured how much I put back in to fill it and came up with 13.75 L (3.63 US gal) but I wasn't able to get all the gas out of the tank that time.

Today I finally used a one-way fuel hand siphon bulb (didn't have this for my first attempt) to more properly drain the tank. I put the AK on the side stand so a bit more of the gas at the bottom was to the side more than under the fuel pump screen. I could feel when the vinyl hose I was using pushed down next to that screen so I am thinking I could get almost all the gas out. This time I put 14.25 L (3.76 US gal) back into the tank. I still think there was likely a little bit of gas in the very bottom under the fuel pump screen and it would be unlikely that I would be able to get that out unless I removed the fuel pump. I'm not wanting to take the bike apart that much just yet. I am satisfied with how much I did today.

During the usual warmer riding season I've been getting around 55 mpg with my AK. Sometimes a few more and sometimes a few less depending if I spend more time on faster harder riding or take it easy on more country roads. This season I've had it up to 57+ mpg while traveling and riding on 55 mph roads with some slower speeds thrown in. That means I can go about 200 miles per tank if I stretch it to the limit. That's comparable to what I was doing on my Burgman 650.

[Stig / Major Tom]

Simple question ...the owner's manual says your scooter's fuel tank capacity is what?
Owner's manuals usually list a scooter's capacities...oil, fuel, gear oil?
Stig

[rjs987]

Simple question ...the owner's manual says your scooter's fuel tank capacity is what?
Owner's manuals usually list a scooter's capacities...oil, fuel, gear oil?
Stig

The owners manual does not show the tank capacity in the specs chart nor anywhere else. A lot of other specs are defined but not that one. Something that I do usually see in other OMs. That's why the question about it on another forum.

The PDF file for the service manual does mention somewhere what the tank capacity is but that manual is for the Euro 4 compliant version and is from the Kymco HQ in Austria (SE of Germany) though it is in English. I am thinking the SM file I have was originally written for the 2017-2020 versions but would still apply to mine since there has really not been much, if any, significant change from 2020.