gas tank swap possible ?

[tirebiter]

I'm trying to figure out if I can extend the range of my GS850GL by putting on a larger gas tank. Does anyone know if there is a tank from another year/model GS that would be a direct bolt-on fit and have increased capacity ?

Mine holds a little over 3 gallons, I believe. Have not drained it completley to see exactly what a fill up would be. I'm having to stop at the gas station more often than I'd like to and putting in just under 3 gallons when the gauge reads about half way down into the red/reserve area.

 

[Steve]

What year is your bike?

The '80 and '81 850L had about a 3.5 gallon tank. The '82 and '83 850L had a 4.5 gallon tank, but it attaches differently.

So, if you don't mind getting creative with a welder, you might be able to adapt.

The only other choice would be to phycially split the tank and add some bits to increase the capacity.

Either way, you will be beaking out the welder.

.

 

[gustovh]

My 850L is, say, a little changed. I run a 750L tank, gives me 4.5, but not running the stock seat. The tank is about an inch plus longer not to contact the forks. That is the best that I have been able to do.

V

 

[tirebiter]

Thanks Steve and Gustov, I'll look into the later GSL tank.

I had a chance to see how far I could go on one tank. I understand the meaning of "reserve" now. The tall screen fuel pickup premixes air with the fuel when you get to about .5 gallon remaining, it seems.

Poor running and no power is not what i want on my bike when I get low on fuel. I'm definitely going to do something about the tall pickup screen. I think I want the engine to run well until it dies as the last few drops of gas are ALL drained from the tank.

For the life of me I cannot fathom why Suzuki wants riders to have poor running on the last several miles of fuel capacity. Some type of idiot-proofing ? Am I an idiot for wanting it to be different ? What's up with this "reserve" thinking ?

 

[tirebiter]

Looked at a GS1000 tank today from a late '70's bike. Same mounts and cap opening, gauge sender and petcock location but definitly an inch longer. Maybe more. Non-stock seat anyway so maybe I can crowd into it. The search for a cheap early GS 1000 tank begins.

 

[rwnielsen]

Thanks Steve and Gustov, I'll look into the later GSL tank.

I had a chance to see how far I could go on one tank. I understand the meaning of "reserve" now. The tall screen fuel pickup premixes air with the fuel when you get to about .5 gallon remaining, it seems.

Poor running and no power is not what i want on my bike when I get low on fuel. I'm definitely going to do something about the tall pickup screen. I think I want the engine to run well until it dies as the last few drops of gas are ALL drained from the tank.

For the life of me I cannot fathom why Suzuki wants riders to have poor running on the last several miles of fuel capacity. Some type of idiot-proofing ? Am I an idiot for wanting it to be different ? What's up with this "reserve" thinking ?

Hold on a second... There's a fuel pickup tube inside the screen. I normal run mode the valve draws from the top of the tube. This leaves a small amount of fuel it can't pick up. In reserve, it draws from the bottom of the tube. Follow me? There's no conspiracy to make your bike run crappy.

 

[Steve]

I understand the meaning of "reserve" now. The tall screen fuel pickup premixes air with the fuel when you get to about .5 gallon remaining, it seems.

That's not quite how it works. There are two tubes inside that screen. In the ON or RUN position, you are drawing fuel through the taller tube. When the level in the tank gets too low, you "run out" of fuel because the tube is higher than the fuel. Switching to REServe will move the inlet to the lower tube, which is basically at the bottom of the tank. There is no "premixing air with the fuel" unless you have a leak somewhere in the system.

For the life of me I cannot fathom why Suzuki wants riders to have poor running on the last several miles of fuel capacity. Some type of idiot-proofing ? Am I an idiot for wanting it to be different ? What's up with this "reserve" thinking ?

Well, let's just say that you seem to be the first one out of the millions of previous owners that has noticed this.

Maybe it's your bike that has a problem?

Let's pose a question to the rest of the forum.
Let's see, by a show of hands, how many of us have accidentally left the petcock on REServe after filling the tank?
Here, I'll be the first to admit it.
During the next 200+ miles that the petcock was in the REServe position, it ran JUST FINE, no "premixing" happening at all.

Looked at a GS1000 tank today from a late '70's bike. Same mounts and cap opening, gauge sender and petcock location but definitly an inch longer. Maybe more. Non-stock seat anyway so maybe I can crowd into it. The search for a cheap early GS 1000 tank begins.

When you get that 1000 tank, make sure there is some sort of return policy on it. :-k

Yeah, it may be only an inch longer, same mounts, etc., but that is not the whole story.

The forks you your L are mounted farther back than the forks on the 1000. That means that when you turn the wheel all the way to either side, you are likely to hit the tank with the forks.

.

 

[steve murdoch]

Leave the petcock on reserve? Today?
Done it lets just say more than once.
More embarrassing is when the the bike sputters and you go to flip it to reserve and find out you are already there. These brutes are heavy.

 

[tirebiter]

OK, I'll check to see what's up with mine. I don't think it's the stock petcock. This one has no reserve or shut-off. It did have a diaphragm at some point, I assume. Sure looks like it did. Regardless, there is none in there now.

Presently, I am running an inline shutoff valve. I capped the carb vacuum outlet and the vacuum port on the petcock. Until I figure out what is stock and when I decide if I do or don't want an automatic-vacuum controlled- petcock, I'm looking into other configurations. Obviously I'll have to have a good look at the pickup tubes inside the screen. Thanks for the lesson Steve.

I spotted an early GS 1000 tank at a swap-meet this pas tweekend and yes, Steve, you are again 100% absolutely right. The 1000 tank is longer in front and would interfere with the fork tubes when turning all the way to either side. NO GOOD !

As an aside ... how does gasoline migrate from one side of the tank to the other especially when you are low on fuel ? It appears as though the two tanks halves are not joined when the fuel gets to less than 1/4 full.

 

[jbird7262]

So what about the "famous" 1980 leverless petcock, where is reserve on that!

 

[Steve]

OK, I'll check to see what's up with mine. I don't think it's the stock petcock. This one has no reserve or shut-off. It did have a diaphragm at some point, I assume. Sure looks like it did. Regardless, there is none in there now.
...
As an aside ... how does gasoline migrate from one side of the tank to the other especially when you are low on fuel ? It appears as though the two tanks halves are not joined when the fuel gets to less than 1/4 full.

You never did answer what year your bike is. If it is an '80, that is likely the "dreaded '80 petcock", and is, indeed, STOCK.

So what about the "famous" 1980 leverless petcock, where is reserve on that!

Your only hope of "REServe" is hoping that your fuel gauge is still working correctly.

You can calibrate the gauge so you know a bit better how much fuel is there. Personally, I like to calibrate it so I have to switch to REServe when the gauge gets to the red line. Since you don't have a REServe position, I would drain the tank completely with the PRIme position (yes, you do have one), then put in a measured 1 or 1,25 gallons and calibrate the gauge from that known quantity of fuel.

.

 

[tirebiter]

My GS850L is a 1980 model "T" built in September 1979. The petcock that came with it has no lever and no markings for "PRIME", "RES" or anything. No slotted screw either. The diaphragm had been removed previously and indeed, this bike did not run when I brought it home in the back of my minivan.

I can post photographs of the petcock if anyone is interested. My take on it is that it is either an aftermarket petcock or from some other bike that uses the same bolt spacing.

This past weekeend when I was at the motorcycle swap-meet, I bought a petcock which it utrns out is not the same bolt spacing. I had a choice between the two and without comparing to another bike there. I wrongly chose the petcock with the larger of the two bolt spacings. For $5 , I'm not complaining, mind you.

I know, I should measure my tank and KNOW what the bolt spacing is since I need to do something about the petcock. Not to self : measure the bolt spacing when I look at the screen on the petcock (actually just an empty full-flow, bolt-on fitting as it is) I'm running now.

I probably will calibrate the fuel gauge at some point. Probably after I either succesfully come up with an increased capacity tank or give up on the idea. The fuel gauge reads full until I get to about 50 miles. Then it drops like a stone for the next 50. I'm about 1/2 way into the red when I fill up at about 110 miles and it takes about 2.7 gallons.

 

[Steve]

I probably will calibrate the fuel gauge at some point. Probably after I either succesfully come up with an increased capacity tank or give up on the idea. The fuel gauge reads full until I get to about 50 miles. Then it drops like a stone for the next 50. I'm about 1/2 way into the red when I fill up at about 110 miles and it takes about 2.7 gallons.

Sounds like it's already pretty well calibrated. Being half-way into the red zone and putting 2.7 gallons into a 3.5 gallon tank sounds good to me.

Gas mileage isn't that far off, either. That is about 40.7mpg, which is not bad, if you are riding "enthusiastically" or just plain fast. The bike gets fantastic mileage when kept under about 70 mph, but it's not all about "miles per gallon", it's all about SMILES per gallon.

.

 

[DanTheMan]

3.2 gals is what my book told me my original tank on my 1980 GS850GLT would hold and it did come with the 2 position vacuum operated petcock, just Run and Prime. You're getting good mileage if you're still putting less than 3.0 gallons in with 110 miles on the clock. I switched out the triple tree on mine, did some welding on the frame, modified the seat mounts, and installed a larger tank and an '81 850G seat. More comfortable, longer range and a petcock with Run, Reserve and Prime. Wire feed welders are awesome tools to have. :welcoming: