Fuel Tank Expansion

[Yamaniac]

Here are a couple pics of my fuel tank being modified. I have a feeling these pics are gonna be large, so apologize ahead of time. that hole down the back is 4 3/16", roughly 2" all the way around. Anybody want to show me a way (mathematically)to get an estimate of how many gallons it'll hold (before I test it)? stocker off an 80 special. 3.97 gal I believe is what the book says. I'm hoping to get around 6 when it is complete. (MODERATOR, FEEL FREE TO RESIZE IF NEED BE. Thanks)

[Mathh]

wow

That takes courage. Wonder were I have seen that before

[fredintoon]

Weigh it?

Hi Yamaniac,
6 USG is about what a Standard tank holds and they bolt straight on but WTF, go for it! I tried jumboizing a fuel tank one time. All I gained was an enormous amount of respect for those who could make a leakproof weld bead. An approximate low-tech way to calculate the tank volume is to make cardboard cut-outs of the tank cross section at 1" intervals, calculate the area of each one in square inches and add them up to give cubic inches. That's a load of calculations. You are going to do a water leak test anyway so weigh the tank full and empty. One US gallon of water weighs 8.34 lbs.
Fred Hill, S'toon.

[Yamaniac]

Math,

Unfortunately, I had already cut into this one when I saw how you cut your tank. I wondered if I should have followed your lead and cut off each side, but the shape of this special tank would not have produced as good of results, in my opinion. The sides are somewhat flat, but still have multiple radius's.

Fred,
I knew that, but I like the special tank look. also, I could spend a long time looking for an 81 standard tank. When complete, this tank will have lines virtually identical to the special from the side, so (hopefully) it will take a keen eye to know the tank has been messed with. Luckily, I have a really good friend who is a certified tig welder. that doesn't guarantee no leaks, but it makes me a little more content that there won't be, and it'll look good too!

Thanks for the opinions, I look forward to more. I did mess up and should have gotten the base bead or soda blasted to get it clean. Looks like I might have to go another route to clean and seal after its finished.

[fredintoon]

Tank cleaning

Hi Yamaniac,
here's a way to clean your tank

http://www.650rider.com/Content/pa=showpage/pid=6.html

good luck with the project.
Fred Hill, S'toon.

[TomB]

I made a tank for a little Honda sprint bike a few years ago,

I welded it with a MIG welder and yep you're right, it was fun trying to get it leak proof.

When I finished the welding I tested it with water and it was perfect, not a leak to be seen, then I put petrol (gas to you lads) in and it p!ssed out everywhere.

How the hell was I going to weld it when it had been full of gas.

I didn't want to go bang.

In the end I washed it out with parrafin (is that kerosene to you lads ) after that welding is OK again.

I only mention that in case you need to go back to tack a pin hole or two, hopefully not.

[Yamaniac]

Oh come on.... where's your sense of ADVENTURE??? Thanks for the tip. I'll definitely keep that in mind.

[Pat Kelly]

Years ago my father built a tank to hold chemicals in a cropduster. The plane was an old biplane and he built the tank to fill the front seat. The tank was irregular shaped and fit around various frame tubes and other protuusions.
I saw he had mounted a gauge to read the level of whatever liquid was in the tank and it was hand-marked at 10 gallon intervals. I was amazed that he had used some kind of formula to determine where the marks would be on the gauge (Dad is a math kinda guy, I'm not). I asked him how he figured out how to mark the gauge and he told me he poured two 5 gallon buckets of water in then made a mark, two more buckets.....

Smart man my Dad. 78 years old and still has his pilots license and instructors license. He trains new pilots on C130 and DC6 for fire-fighting. He was in the James Bond movie "The Living Daylights". He was flying the C123 (C130 in the movie) while the stuntmen were fighting on the cargo net out the back of the plane. When the bad guy falls you get one brief shot of the plane and you see only 2 props and 2 jet pods (C123).

Back on topic, your tank looks good.

[Yamaniac]

Thanks for the story, and tank comments Pat. Any wise tips or tricks from anyone is
appreciated. I was kinda hoping for some more critiquing of it from the members...

The whole reason for the project is to hopefully be able to ride and fill at the same time as
HD's and Goldwings (long trips). Most everyone I ride with now rides HD, except for the
one GW. After some figuring, I only use about 3 gal of my tank now before bike starts
coughing and acting like it's out of gas. That leaves one gallon in the tank. On that same
thought basis, 6 gal capacity, 5 gal 'usable' at 30mpg- 150 miles.... roughly what an
HD will do.

On another note, Fred, I 'plan' to have it bead or soda blasted, and then to Red-Kote to
seal it. Thought about electrolosis, but I think the other way might be better off for
the long run

Thanks again,
Theron

[fredintoon]

But - - -

- - - you said:-
did mess up and should have gotten the base bead or soda blasted to get it clean. Looks like I might have to go another route to clean and seal after its finished.
- - - And now the photos show the tank at least partially assembled. So how you gonna blast clean inside there?
Fred Hill, S'toon.

[Yamaniac]

I still have a 4" gap down the middle back of it, and the bottoms out of each side. The plan is to get the bottoms tacked up,
blast it, clean out residue, wd40 or some other light oil to prevent flash rusting, sew up the top, weld it up tight, check
for leaks, re oil, body work, acetone and or alcohol, Redkote, prime, seal, paint basex3, paint Kandyx5-7, clearx10 or so.

That may not be exactly how it goes, but it still has 3 gaping holes in it and at least one of them is gonna stay open so
I can get all that old metal CLEAN.

I do see your point about the way I wrote things, though. What I was meaning and didn't say was that I should have blasted
it when the tank was in 3 pieces instead of waiting to start rebuilding.

Clear as mud, right!

[fredintoon]

Blast-cleaned steel REALLY wants to rust.

Hi Theron,
if you can still get the blast stream onto the tank innards, good. Like the header sez; that steel will be trying to rust from the minute you stop cleaning it. Be prepared to de-rust the inside of the tank once you are done & perhaps phosphate coat it right away.
Fred Hill, S'toon.

[Geezer]

It sure looks like a fun project. I have 3 rather screwed XS11 Standard tanks that I'm saving until I have the time (and power for my welder) to build one larger tank out of. It's really a moot point as I never ride more than 150 miles before I need to stop and stretch and I plan my fuel stops around that.

This used to be a common project for endurance racers but I haven't seen anybody do make a tank like this in years.

Geezer

[EZMoney]

Good idea
I have been thinking of making a bigger tank since I got my first one XS last year. The 80 special I just picked up had a dented tank and I got a better one from Andreas so I have a spare to play with.
One question about the expansion, I noticed that the back of the tank is quite wide and squared off, how is that going to be comfort wise? I am not that tall and would have trouble with my knees sticking too far out. Just wondering.

Ed

[Yamaniac]

Geezer,

I'm sure there are a 1001 ways to expand them, but for the standard, I personally liked the way Mathh did his. there
are a bunch of pics of that on the UK XS11 site, I believe. Of course, if you wanted to ship one down here, I would
be more than happy to 'test' it out. Of course, the bike to test it on is completely stripped right now, so it might be about
5 years or better before you get the tank back. I really can't take any credit for the design...A friend of mine, actually the dad of one of my buddies, is just an outstanding fabricator, and painter, and mechanic. He is the one 'helping' me with it. All I have really done so far is chop up the tank, fit some poster board, and cut some sheet metal, all under his wise supervision. I feel like I have learned much from him, for which I am lucky and thankful.

Ed,
for a shorter person, I don't know how it will be. I am long legged, so for me it shouldn't be a problem. I find myself riding with my knees out catching wind most often, but I should still be able to hug the tank with my legs if need be, and probably a little more comfortably (for me). In reality, the tank sticks out 2" further on each side, so I can't imagine it being too much of a problem for anyone. Might stick SWMBO on there to test on someone 5'5". Most of that will be covered by the seat anyway. It is a valid concern though, and I'll take a look tomorrow to see. We were going to just raise the front (and not the back) but ran into problems with the triple tree hitting. as of now, there is about a 1/16 clearance.

Fred, thanks for the heads up there. I wanted to just coat it with oil or something to keep it from flash rusting until I was done with body work. I had read somewhere not to seal the tank until all the bodywork was done. Guess I might have to rethink that whole strategy some before I get too much further.

Again, thanks for all the input guys. I appreciate the comments, and would like to hear some dissenting views, as well.

Theron