Filling Fuel Tank

[1216]

I notice that when the RT tank is "full" I can squeeze a bit more gas into the tank by filling it mid-way up the "neck". The fuel runs down into the tank. I have repeated the process several times, but never to the point I could not get anymore gas in the tank. I can get four more gallons in my GMC pick-up this way, but know it is probaby not a good idea on the RT. Has anybody else noticed this? How much extra fuel can you get in the tank this way?

[Alan D]

If you get too much fuel in it and it runs down into the carbon canister you may eventually develop a problem.

A search on this board will probably explain it better.

[313_Matt]

Speaking from an environmentalist point of view, overfilling gas tanks is bad. The extra gas doesn't actually do anything for you - it usually runs out onto the road or (as mentioned above) into your carbon can.

 

Don't believe me? Check out the EPA:

http://www.epa.gov/donttopoff/

 

313-Matt

[Paul_Burkett]

If you are on a mission to some where, you can do a canisterectomy and then very carefully pull the fill neck out of the tank and drill a 3/8 inch hole in the fill neck, about one inch from the top. Watch out for metal schards falling back into the tank, then reinstall the fill neck. You can get 0.4 gallons of gs into the tank, but when you fill all of the way up, you had better take off right away or the gas will come up and over the top and down the over flow holes in the top of the fill neck.

[Tri750]

If you are on a trip, wiggle the bike back and forth gently to get rid of any air pockets and to get a full tank and get back on the road. If you are just gassing up before parking the bike, its not good to overfill as the fuel will expand as the sun heats up the tank or thru heat soaking when parked and foul your cannister.

[Ken H.]

Unless you are on some type of an endurance run or something, what's the point? Is .2 gallons of additional capacity going to materially degrade your riding?

 

The restricted fill level is there for a reason - emissions control. If it ain't broke don't fix it!

[russell_bynum]

If you are on a mission to some where, you can do a canisterectomy and then very carefully pull the fill neck out of the tank and drill a 3/8 inch hole in the fill neck, about one inch from the top. Watch out for metal schards falling back into the tank, then reinstall the fill neck. You can get 0.4 gallons of gs into the tank, but when you fill all of the way up, you had better take off right away or the gas will come up and over the top and down the over flow holes in the top of the fill neck.

 

Correct. Lisa's R1100RS's canister was dumping nasty black crud into the TB's, so I did a canisterectomy. I also drilled the filler neck.

 

On a warm day, if you fill the tank completely, the fuel WILL expand and leak out of the overflow tubes. This is a bad thing for obvious reasons. However, in playing with it a bit, I found that I could fill about halfway up the neck and as long as the bike was parked on the centerstand, it doesn't expand enough to leak out. You really don't gain that much extra capacity (maybe 1/4 gallon or so), but it does fill easier and I get some extra piece of mind knowing that I've got another 1/4 gallon (~10 miles) should I need it.

[DavidEBSmith]

Is .2 gallons of additional capacity going to materially degrade your riding?

 

That's 8 miles. It can make for a bad day if you run out of gas 7 miles from the gas station. Not that anybody would ever make the error of waiting too long to fill up, or getting to the exit to find the station to be closed.

[Paul Mihalka]

On my R1150R I did the neck drilling and gained a possible .4 gal. On my regular commute route (75 miles/day) there is only one gas station that I like. The rest are 15 to 20 cents/gal above average. With the overfilled tank I can do three days, otherwise only two days of commuting.

[1216]

While putting the extra fuel in my truck is meaningful, I agree it doesn't make too much difference in this case. I do track my gas mileage and a few tenths of a gallon can make a difference in the calculated mpg. The thing I need to do is be consistent. I guess in the future I will stop as soon as the fuel reaches the base of the neck.

[Scarecrow]

Some while ago, I thought I saw a thread about replacing the 1150 tank fill neck with one from an 1100. This was supposed to essentially have the same result. Am I dreaming or is that a possibility?

[Softtail]

Thanks for this post, this is something I have wondered about for some time. I always try to squeeze as much fuel in as possible, fill it to the brim a shake it etc. Now it sounds like that may not be a real good idea. I will definately be loosing the carbon canister. I guess all you have to do is plug the connection to the TB and route the drain/overflow to daylight, somewhere inconspicuous.<<<Softtail>>>>>

[EricJRW]

I started this at work a fews days ago and forgot to finish (as I wanted to confirm the numbers):

 

Interesting...

 

Not sure I completely agree with donttopoff.com, as I suspect we all pull the nozzle out as we continue to fill, thus only vapors are sucked back into the recovery system...

 

I am however curious about the canister, as this seems like a greater danger. I have also done my best to "fill it to the rim" (i.e. the lowest part of the "neck"), especially when setting out on another long run. I have also (one or twice) overfilled, and watched it dribble out the overflow tube under the bike (seems this is bad).

 

What I have noticed, if I just fill until the gas shuts of by itself, is that the first bar on the bike's fuel gauge will be gone in about 5 miles (for this observation, I also filled on the side-stand, not center). If I fill it to the bottom of neck on the center stand (which, as mentioned above, requires allowing the gas to settle and add more, repeat) it will be about 20 miles before the first bar is removed. At ~45 MPG, this would indicate about 0.3 gallons difference.

 

But back to canister: How does the fuel get into the can? I thought this too was to scrub vapors so that they are not released into the air, but where exactly are the vapors collected from? Information here seems to indicate that liquid fuel can also get in the can? Does filling to the bottom of neck really cause problems? I read a post regarding if you "modified the filler neck", but is this really a problem on a stock bike? As I read more threads by searching "canisterectomy", I start to get really nervous…

 

Thanks,

 

Eric

[No_Twilight]

 

Not sure which obvious reason your mean but the overflow tubes are near the right foot, in front of the rear tire (assuming you've had a canisterectomy). A couple of months ago I filled up at a station that had no fume sucker and I noticed the tank was full to the bottom of the neck. It is usuallly about 1/2" below the neck. I then spun out and crashed on a gentle turn going slowly (about 50mph). Afterward, the rear tire was shiney from some solvent. I have two theories: 1. For some reason, my full tank overflowed onto the street right in front of my rear tire. 2. The nice trucker in front of me who stopped to see if I was ok had actually spilled some diesel. Either way, it had evaporated by the time I went to look at the crash area 15 minutes later.

 

I don't know if I spun myself out or not but I would be very careful about overfilling the tank.

 

And BTW, I get 200 miles on a not so full tank. I keep going quite a ways after I have no bars on my fuel gauge. The yellow light reminds me to watch my trip odometer that I reset when I get gas. I know that I have 5.5 gallons or so and get 40 mpg so going 200 miles leaves me with some margin.

 

Cheers,

Jerry (R11RS)

[EricJRW]

I'd like to see a diagram that shows how all these hoses connect... Being able to visualize this would be a big plus...

[Wooster]

Eric,

 

There is a very useful diagram and discussion on removing the canister (those of us having seen ER on TV refer to this as "canisterectomy"). Last spring, I "did a search" at this site (I think I specified 2 year time frame) and got very clear diagram as well as verbage; resultant operation was simple though I could see the potential for confusing the various hoses w/o the diagram. Lastly, several surgeons have found the small rubber covered brass caps listed for K bike's fuel injectors to be just the thing for sealing off the vacume spigot on RT fuel injectors.

 

Wooster w/o canister

[Ken H.]

The intake fumes pickup point for the hose going to the canister is at the very top of the tank. Under normal conditions the cannister indeed can not get liquid fuel into it. It can only happen under certain abnormal conditions; The bike experiences a sever lean angle (e.g. a tip over while not while in motion), or over-ambitious attempts to put more fuel into the tank than it was designed to hold. Either by topping off or modifying the fuel fill system. E.g. - drilling out the filler neck.

 

IMHO the often quoted threat to the bike from charcoal canister failure (including the photo often posted/sited here) is largely an 'urban myth.' Any teeny-tiny amount of liquid fuel that may migrate into the system will quickly evaporate by the air flowing in the cannister system and be drawn into the intake as fumes.

 

The real source of disintegrating canisters is people mixing up the filler drain hose with the tank vent hose during service causing rain or other water to flow into the canister. Which of course will destroy it. Hardly a failure of the system nor a justifiable reason to defeat it (i.e. do a "canisterectomy") and contribute to air pollution.

[DavidEBSmith]

Canisterectomy instructions with hose routing diagram are here.

 

As to the risk of charcoal canister failure, I can tell you that the last time the fuel tank was off my bike (when it still had the charcoal canister), it had lots of charcoal-like black stuff in it. So whatever the failure mechanism or abnormal condition was, a solution was to remove the source of charcoal.