Auxiliary gas tank for more range

[t3rmin]

So my 700 has a fairly small tank with about 130mi range (including reserve). What's more, I'd like to do some performance mods in the future which will undoubtedly reduce my gas mileage somewhat.

The problem is I like nice long rides and frequent gas stops are annoying, and in some scenarios, not possible.

Another thing I like is the high gas tanks on newer sport bikes. Laying down on the tank is a nice change-up on a long ride. I know people utilize tank bags as risers so you can do that even with a low tank.

Anyway, I was wondering if anyone has ever considered an auxiliary gas tank in a tank bag? Would kill two birds with one stone for me.

Obviously it'd have to be secure sitting there, and not any more prone to leaking than the real tank is. So something with a nice vented cap and a shut-off valve and rated for gas (like a normal tank). I'm thinking a line from the aux tank to a V before the carbs would work fine. Done right, I don't see why it'd be any more dangerous -- after all we already have a gas tank between our legs...

The other option would be to fit a larger tank to the bike. But I really like the stock look and stock paint/decals, plus I don't really have any ability to fabricate and I doubt anything is an easy bolt-on...

 

[onchiman]

I wonder how that might effect handling with the load being up high like that? It might not be too bad with only a gallon or so but 3 or 4 gallons might have an undesireable effect. I suppose you could pack your tank bag with 25 pounds of weight which would be near the weight of 4 gallons of gas then ride around a bit. If you're running pod air filters and have removed the airbox, that would be a good place to locate an auxilliary tank. Using the under seat space and maybe relocate some of the electrics I'll bet a nice aux tank could be fabricated under there.

 

[t3rmin]

Well I was thinkin' about only a gallon or two in the aux tank. The main tank holds less than 4 gallons I think, so even one gallon would be a major increase.

I thought about putting the aux tank under the seat somewhere, but since these bikes are gravity fed it wouldn't work without installing a fuel pump. Gotta keep the tank above the carbs.

 

[erdmania]

I think 25 lbs up high is not really a problem. I regularly carry more weight than that in my tank bag without adversely affecting handling. Old GSs have a pretty high center of gravity to begin with, then there's 200lb me on top of it all. At least in my case, extra weight on top of the tank is probably more of a good thing than bad since it puts a little more weight toward the nose of the bike.

But I think the real solution here would be to fit on a larger tank and skip the aux in a bag, which just sounds dangerous to me. You can always copy the look (decals and paint) of the original tank on the bigger one.

These of course are just my opinions.

 

[t3rmin]

In that vein, anybody know the closest-to-bold-on larger tank for the 700? Maybe the 1150?

*edit* Not the 1150... looks like it bolts on the side?

 

[t3rmin]

The other reason I like the aux tank idea is it's easily reversible. Slap it on when I go touring, but leave the bike sleek and stock around town.

 

[bwringer]

Some of the Iron Butt guys have added aux tanks to all sorts of machinery -- you might do some Googling and see if you can find some photos of their setups.

FJR owners seem to especially prone to tinkering -- I've seen photos of a very sanitary FJR setup that placed an aluminum aux tank on the rear rack in place of the trunk. Solenoid valves and everything. I think he also had an abbreviated trunk or some way to carry stuff back there. There's an FJR forum somewhere, but I don't have the link.

There was another guy who did Iron Butt events on a ZX11 with a fuel tank that had been extended vertically to the point where he could barely see over it. He covered the extension with nylon or Naugahyde so it would look like a huge tank bag. Some crazy stuff out there.

The tank bag idea doesn't seem quite right to me -- I really don't like the idea of a fuel tank surrounded by a material that could absorb gasoline, for one, and I also don't like the idea of a tank that isn't bolted in place.

Maybe a rear rack with jerrycans? You'd have to stop and fill up, although you wouldn't need a gas station.

You'll also want to look into an EZ Leaker, too...

 

[t3rmin]

Yeah a tank on the back would work too. If I can ever locate a stinkin' rack for this mono-shock bike, that is. Or maybe one could be lashed to the back grab rail. I'm seeing some nice cylindrical ones that might work well for that. A small aluminum cylindrical tank on each side lashed to the grab rails might look neat, actually.

I don't want one that takes up the back seat (so the wife can ride), and I don't want jerry cans so I have to stop -- that just wouldn't be nifty enough. ;-)

 

[jpaul]

You can try this place for ideas.

http://sampson-sporttouring.com/index.html

I know a guy who made his own for his Kawasaki Voyager XII. Went back behind the rear wheel. He just added a pump to transfer the gas to his main tank. One that fit on the rear seat, similar to the EZ tank on the web site, would probably be your best choice. A Y connection on the fuel line would be a relatively simple and reversible installation. Take it off if your wife is going to be riding with you. She probably isn't as interested in the extra range as you are anyway.

 

[crag antler]

Here's one from Sampson for the Connie.

Holds like 4 gallons

 

[txironhead]

Since you're going to be modding it anyway, how about this:

Convert to pods and jet the carbs accordingly. Then find a tank that fits where the airbox originally sat. Hook up a fuel pump (similar to how the turbo guys do it) and toss the factory petcock (cap the carb vacuum port). Have the factory tank "drain" into the secondary tank, and have the secondary tank hooked up to the fuel pump. The factory tank screen can be kept to filter the gas, and some type of petcock/reserve system could be hooked up inside the auxilary tank.

This way, the extra weight is kept lower, you're replacing the airbox with a tank so there's nothing "extra" mounted to the bike, you don't have to worry about the petcock leaking and hydrolocking your engine (fuel pump quits when bike's not running = no flooded cylinders), and you've got a setup very similar to the factory setup on an '85 Honda Shadow. You could probably even get the fuel sending unit from said bike and adapt it to fit this setup. On the Shadow, once the primary tank was empty and the bike was running on the reserve tank, a light on the dash would come on notifying you that you needed to refuel soon. I found out rather quickly that my fuel sending unit didn't work........that was a long walk.

 

[highmileage]

This is low budget and low tech. On my GS 1000 GL, the tank is particularly small IMHO. On those occasions when I sill be riding a long ways and may not be able to get gas (or gas that i want, since I refuse to use ethanol blends) I have a 1 1/2 gallon plastic gas can that fits quite nicely into my expandable bag that I keep behind the seat.

It's not hooked up to anything, I just pour some into the tank when I get low. Get lots of funny looks when I put gas in there w/o taking the can out and stting it on the ground like I'm supposed to.

And I still have quite a fair amount of storage in the side pockets when i expand them out.

 

[t3rmin]

txironhead: I wonder if I'd have any issues using a fuel pump with the stock carbs? Like it wouldn't force fuel past the floats or anything...? I really would love to have the tank under the seat, for all the reasons mentioned.

The other thing I thought of was a tank under the seat and a fuel pump, but it just "refuels" the stock tank. Flip a switch when you get low and a few extra gallons are pumped into your stock tank.

 

[txironhead]

You'd have to run a regulator set pretty low, but I don't think it would be a problem. I had carbs on my Shadow.

You could do the "refill" technique, but then that would require filling two tanks instead of just one. Completely up to you. But I really wouldn't worry about the pump overpowering the carbs. With a very small pump and a regulator you're just overcoming gravity.

I've often wondered why no one did this with the Intruders since they have notoriously small tanks (especially for a 1400cc engine), but I did a search and there is an aftermarket kit for the Intruder, as well as oversized tanks. You might do a Google for auxilary fuel tanks and see what pops up.

 

[SPARKSS]

I sure hear ya about the range! My 79 GS1000 only gets about 120 mi to the tank (200 km) and I better be coasting into a gas stop at that point. I like to tour and have sometimes found myself in remote areas where I wasn't sure where the next fuel was going to be and on one occasion I carried two extra 2gal jerry cans slung one each side on the rear (and was thinking that a pair of hard bags would have been an ideal mount for these).
That basically doubled my range allowing me to concentrate on the trip. As for plumbing something like that in, I'd have a hard think about that.....First, your main tank uses a vacuum opened fuel valve so that it "should" shut off when the engine isn't running. Secondly is the failure mode of anything you add to your bike and where stray fuel leaking might affect other systems. At least with the jerry can idea (or similar) you get a chance to get off and stretch your legs while refueling (and enjoying that scenery out in the middle of nowhere which is where you ran out!).

 

[t3rmin]

Yeah when it's all said and done I'll probably end up with cans. But I like to dream. ;-)

 

[moto_dan]

So my 700 has a fairly small tank with about 130mi range (including reserve).

Your mileage seems especially low for your 700. I ride my '83 750 pretty fast most days and get around 36mpg. so with a 5 gal. tank(same size as yours I think) that calculates to 180 mile range. I hit reserve with .8 gal left(around 152 miles). My mods are a 4-1 pipe, stage 3 jet kit and K&N pods. With factory air box and the factory lean jets your mileage should be in the 40's unless you're keeping her pinned most of the time or idling excessively in traffic. IMO.

But as to your question as to extra fuel capacity others have offered several viable suggetions. I wouldn't however carry extra fuel in a backpack as was suggested from another site, hopefully made in jest.:shock:

 

[t3rmin]

My tank is most certainly NOT 5 gallons! It's in the high 3 to low 4 gallon range (I've read conflicting information). One look at the tank and it's obviously fairly small. The bike is running great. Well it was before the camchain broke. ;-)

 

[t3rmin]

Also 130 miles was a very conservative estimate based on the fact that I do not like running out of gas. ;-)

 

[DanTheMan]

My 850L came out with a 3.4 gal tank, which has let me run, on occasion, as far as 125 miles. There is no reserve either. When I did my ride west, I carried a 2.5 gal plastic gas can in my trunk, and used it three times. Most of the time here in the Midwest, there are enough gas stations to stop every 90-110 miles, refill and stretch. I would like a 5 gal tank though:-|........