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Discussion Starter · #1 ·
Manual says we are supposed to fill the tank to that flat bottom metal piece in the filler neck.


I read some post in here where someone got nearly 3/4 of a gallon MORE into their AT fuel tank filling it to the brim.

What happens if you fill the tank so full you barely get the cap down without it spilling out?
 

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On other bikes I've owned, over filling can cause gas to leak out of various breather tubes and potentially cause vapor lock. Probably the same thing here.

I don't see getting 3/4 of a gallon. I mean it's like... 3/4 of a cup at most. You might get more without crossing the metal by putting it up on the center stand.

But I have an ATAS. I run out of ass before I run out of gas.
 

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2022 Africa Twin Manual. R380B.
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I think it will bleed by the breather and drain to the floor.
The fuel needs certain room to expand, specially in hot climates.
Another risk is raw fuel leak into the Canister System, floods the Canister, damages it, and risk of exploding it.
In cars, when the canister get wet, the activated charcoal inside it, expands, breaks their container, and carbon particles are sucked to the engine, clogging the Evap Solenoid Purge, and making very hard starts.
 

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Quite often when filling the tank it can appear to reach the metal bottom of the filler neck, but some how keep filling with fuel. But that’s air displacement making way for fuel, so their is a few seconds where it appears the tank is taking more than it should, is that what you meant?

In terms of what happens when over filling, exactly what @rustynut2 said, it will vent through the breather tube which runs from a small hole at the top of the neck and down a rubber tube to near the left foot peg.
 

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Can't count the number of times I've overfilled any motorcycle tank - but not to the point of spillage ( ... well, maybe a couple times). Decades and decades, including the recent Africa Twin: No issues, except as ol' Rusty Nut says ... a waste of gasoline.
 

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2022 CRF1100 ATAS ES DCT
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I know you use small gallons in the USA compared to us over here but I find it hard to see how you could get 3/4 gallon in the top part of the tank from plate upwards. As someone mentioned you would get more in if you have the bike upright when filling but even then I can't see it being 3/4 gallon.
 

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I know you use small gallons in the USA compared to us over here but I find it hard to see how you could get 3/4 gallon in the top part of the tank from plate upwards. As someone mentioned you would get more in if you have the bike upright when filling but even then I can't see it being 3/4 gallon.
Either way, it is much. Maybe 0.75 liters might be practical - at least that is about what I was able to do on last night's ride.
 

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I think my 22 atas takes 1 more liter when filling up til the top, that's about 26 liter total. I do it all the time, no spills, no problems.

Can't count the number of times I've overfilled any motorcycle tank - but not to the point of spillage ( ... well, maybe a couple times). Decades and decades, including the recent Africa Twin: No issues, except as ol' Rusty Nut says ... a waste of gasoline.
Same here. What I don't do is overfill and let the bike seating in the sun when hot.
Did it once on a KTM 990 and it was a mess

Right now, while I write, my ATAS is filled til the top, seating in the shop and has been like that since yesterday. 4°C right now and we expect no more than 10°C today so I am not worried at all
 

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the 3/4 gal figure seems about right to me. i always fill my bikes while sitting on them in the upright position. i am guilty of the overfill. first fill-up on the bike and the tft said i had used 6gal so i figured i needed to put 6gal back in it because surely the dealer knew what they were doing when they prepped the bike with fuel. at about 5 gal in to the fill-up and i was at the metal plate so i figured that was irrelevant to top off level. pretty sure i got almost another gal in past the plate without overflowing. thanks for the post, i will no longer fill it to that level.
 

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The bottom of the fill sleeve is located where it is to leave some volume in the tank for gas volumetric expansion with temperature. The term for this unfilled volume is ullage (the Forum's word for the day last February 12th). If you fill the tank past the bottom of this sleeve you will have less room for expansion. If the gas expands too much, it will completely fill the tank and any excess will leak past the rubber seal and flow down the drain tube by the left foot peg. Unless, as @rustynut2 points out above, it is clogged with crap. :)

Leave your fully-gassed AT out in the sun for a few hours on a hot day and you will see the gas drip down the drain tube. When I'm riding, I will routinely fill past the bottom of the sleeve, usually about 1/2 way to the top. The bike will use the fuel faster than it can expand and spill out.
 

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My bike is garaged, so no hot sun usually to cause expansion .....I habitually fill to the top of the neck (or close to) after a ride and before I park. I prefer to have the bike ready to roll immediatly for the next round.

I always fill to the top of the neck when mid ride. If I do plan to park in the sun immediately after a gas stop then I will go only to bottom of neck.

I rarely, as in never, see over flow.
 

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2016 Africa Twin 1000A/D DCT/ABS
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On other bikes I've owned, over filling can cause gas to leak out of various breather tubes and potentially cause vapor lock. Probably the same thing here.

I don't see getting 3/4 of a gallon. I mean it's like... 3/4 of a cup at most. You might get more without crossing the metal by putting it up on the center stand.

But I have an ATAS. I run out of ass before I run out of gas.
Oh so true. I just did a 6,500 mile trip on my 2016 AF and it has an even smaller 4.96 gal tank. My azz and legs were run out before I had to stop for gas, and I was doing 80+ all the way so I only got 125 to 150 miles at most before I filled up, only once did I take the bike to flashing 0.8 gal to go. And I have Seat Concepts Rally Comfort seat with a sheepskin cover!
 

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Oh so true. I just did a 6,500 mile trip on my 2016 AF and it has an even smaller 4.96 gal tank. My ass and legs were run out before I had to stop for gas, and I was doing 80+ all the way so I only got 125 to 150 miles at most before I filled up, only once did I take the bike to flashing 0.8 gal to go. And I have Seat Concepts Rally Comfort seat with a sheepskin cover!
Here's what Ol Red has provided over the last almost 3 years:

Font Rectangle Material property Screenshot Parallel


Note that the nearly 53 MPG we got about a year ago was from putting around on the COBDR in 1st and 2nd gear. The AT gets really good MPG in 1st and 2nd gear.

The app I use on my iPhone is Road Trip. An absolutely bitchin app for tracking vehicle costs and maintenance reminders.

W2
 

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Here's what Ol Red has provided over the last almost 3 years:

View attachment 73370

Note that the nearly 53 MPG we got about a year ago was from putting around on the COBDR in 1st and 2nd gear. The AT gets really good MPG in 1st and 2nd gear.

The app I use on my iPhone is Road Trip. An absolutely bitchin app for tracking vehicle costs and maintenance reminders.

W2

I started using this app myself just a littler more than month ago and you're right, it's quite good.
 
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