Larger fuel tank

[andyvh1959]

larger, like at least six gallons, maybe closer to seven. My BMWs have at least six gallons, and in fact my R1200RT carries nearly seven gallons. With 45 mpg being common I get great range before I have to find a gas stop. Not so wiht my 1600 Classic. On a really good day I might get 40 mpg, so by 160 miles the fuel light is on, making me look for a gas stop. For my type of riding 160 miles comes up pretty quick, or so it feels.

I searched the forum for "fuel tank" in regards to a larger fuel tank,and found nothing so I'll start a thread. 1st off, I plan to install a frame mounted fairing, and I have a pair of Mean Streak fuel tanks I got cheap on CL for $30. So I have lots of curvy formed metal to work with, and a buddy with TIG welding capability. The frame mount fairing would block the profile of larger tank.

Based on rough measurements, I estimate a wedge shaped section taken from the MS tanks, welded into the Classic fuel tank after it is cut to raise the front of the tank three inches, could get me close to seven gallons of fuel capacity. I'd leave the back end of the tank, where it meets the seat, as is. From that point cut horizontally forward on the tank to the frame notch area. Leaving the underside of the tank as is, raise the front of the tank about 3" and use sections of the MS tanks to fill in the wedge. The trick is, of course, the compound curves of the lovely stock tank shape on the Classic.

If this is possible, the top of the Classic tank, the filler, the center console, would angle up to the front steeper than stock. The bottom of the tank, the mounts, the fuel pump, etc, would all remain stock. Just add a wedge shape to increase the tank capacity. Close to seven gallons, figuring six before the low fuel light comes on, even at 38mpg would give a range of 228 miles before needing to find fuel.

Wild ass idea? Sure, another 1.5 gallons of fuel adds twelve pounds, but the Classic carries a lot of weight down low enough to counter that effect. After 60 miles from full the bike would feel like it does now with the stock fuel capacity.

[Monkeyman]

Will the in tank fuel system components be compatible? Like, isn't there some sort of sending unit or something that reaches the bottom of the tank?

[Sabre-t]

Why stop at 6 gallons? With this you could go up to almost 9 gallons...

https://www.amazon.com/Sandstorm-Motorcycle-Auxiliary-Center-Aluminum/dp/B00O17OCX4

[Kawi_addict]

Originally Posted by Sabre-t

Why stop at 6 gallons? With this you could go up to almost 9 gallons...

https://www.amazon.com/Sandstorm-Motorcycle-Auxiliary-Center-Aluminum/dp/B00O17OCX4

[Kawi_addict]

I would look into a custom body shop. Have them cut the tank exactly in half then add several inches to the sides trying to add to the depth but keep the original curvature 7 gallon tank could be had for $400-500 I would think

[andyvh1959]

That's why I bought the two Mean Streak tanks. For one, two undented tanks for $30 gives me a lot of pre-curved metal to work from. I figure my buddy can get what's needed to maintain the lovely tank curves with reduced material fabrication (like an English Wheel tooling or a hammer/sand bag).

As far as the fuel level sending unit, it would remain as is. It would just take some time longer before the fuel level would get low enough to register something less than full. The stock fuel level indicator on the Classic center console kinda reads one bar per gallon. After the mods it would just register "full" for over 80 miles before the first bar would disappear.

[Monkeyman]

Originally Posted by andyvh1959

As far as the fuel level sending unit, it would remain as is. It would just take some time longer before the fuel level would get low enough to register something less than full. The stock fuel level indicator on the Classic center console kinda reads one bar per gallon. After the mods it would just register "full" for over 80 miles before the first bar would disappear.

I think you've got that backwards. If the sending unit normally ends at the bottom of the tank, it would show empty when it's actually empty. If you make the tank taller and use the same sending unit, it would start dropping from full immediately (just like a stock tank) but at a 1/2 tank (assuming you double the height of the tank), it would read empty as the sending unit would be bottomed out. You wouldn't have any idea how much gas you had left for the 2nd half of the tank.

[andyvh1959]

Right, the sending unit ends its lowest swing of the float when the fuel is lowest in the tank. I'd not change any of that. The sending unit stays in it's original position in the stock tank. I'd not change the position or mounting of the sending unit relative to the bottom or hump underside of the stock fuel tank. Yes, if I'd mount the sending unit higher after the mods, then I'd never know when the tank is near empty

The float arm swings up to a stop position to indicate the full level. At near empty the float swing arm is down toward the bottom of the tank. My plan is to simply add more fuel volume above the upper stop limit of the fuel sending unit. With more fuel above the upper travel range of the sending unit float means it would stay up, and read full longer. Once the added fuel volume is used up, the float starts to drop as it would in the stock fuel tank volume. When filling the modified tank the float on the swing arm starts to lift as the fuel level increases. As the fuel volume continues higher after the float arm has reached its upper swing limit, the float arm would simply stay in the "Full" position up as the fuel level increases above it. The float, being a sealed volume lighter than the fuel, would just stay high in the fuel volume, even with fuel above it. As the level drops to a point that the float arm moves off the FULL position, the gauge starts to register fuel used. Once the fuel is below the added volume level the sending unit operates just as it would in the stock tank volume.

[alwhite00]

On my 2000 nomad I always wanted to find another same tank and cut them and piggyback them lifting the front of the new tank up a few inches. Then only one seam to deal with. 4.2 gallons sucks for touring.

Never happened though. Never found a tank in decent shape.

[andyvh1959]

Right. Leave the bottom half of the tank exactly as stock. Cut the bottom half of one tank slightly above the mid-horizontal line. Cut the other tank slightly below the mid-horizontal line. Stack one above the other, TIG weld them together and refinish. There will be some metal fab at the top of the tank hump over the frame, behind the steering head area, to fill in that zone. I have two extra tanks, lots of material for that.

To look right though, just lifting the entire top of the tank higher will make it look too fat in profile. Raise the front of the tank 3", raise the rear of the tank maybe 1", to maintain the wedge profile. I agree any Nomad, Voyager, maybe even the Vaquero should have at least six gallons before indicating low fuel. The Classic and Mean Streak models were good with the smaller fuel capacity. The Yamaha Star Eluder has a 6.6 gallon tank. HD Ultra Classic has a 6 gallon tank. Gold Wing carries 6.6 gallons. Most large touring bikes carry six to seven gallons of fuel.

[DragonLady58]

Had a Bud have a custom tank built, went from 4.2 gallons to 5.5 for $550. More or less cut tank in 1/2 horizonally, added 1 1/2" at the rear, 3 1/2 at the front vertically. It felt bigger without being too overly so....
Me myself, I have added a small 1 to 2 gallon under the battery box (nice little cubby hole under there), added a external fuel pump, so when almost empty, I have the pump putting that extra fuel into the tank, via the return line. I put a small 1 way solenoid at the tee, and wire it and pump into the handle bar switch. That way, while riding, I just hit the button, pump up the fuel, I can verify added fuel with my fuel gauge....
Its nice to have but is easy to forget about when a rushed fuel stop happens.....
I have also seen a couple of small tanks made from SS fit inside of the rear crash bars on each side, (looked killer)....but you could wrap with leather for a custom look....both tanks feeding the other tank under the battery box. Can easily get a coupe of gallons....

[Monkeyman]

Originally Posted by andyvh1959

The float arm swings up to a stop position to indicate the full level.

AH. For some reason, I thought the float arm was mounted from above, hanging DOWN. My bad.

[andyvh1959]

No sweat. We're on the same page now. I fact, I think the float assembly mounts to the inside of the tank hump over the frame. Even so, that part of the tank will remain stock, and I'll add volume above. I think a nearly seven gallon tank is possible.

[degreaser]

I would say if you can get a 7 gallon tank out of this project, you're the man, and paint 'er up nice and pretty too

[andyvh1959]

At the very least it'll have at least a gallon more than stock. LOTS of plans for this bike. Never thought I'd care to ride a big v-twin cruiser, but I've really gotten to like this Classic. When I'm done with it, if ever, it'll be up to date with a lot of much newer big cruiser touring vtwins.