www.boxertrix.com

Here's a photographic essay of how I modified my fuel tank to hold 24litres from empty. You'll have to excuse the welding I'm somewhat the novice at TIG and some of the welds were pretty awkward.

Marked the tank for cutting. I wanted to use as much space as possible and still leave room around the alternator and pump plate

***ALL PICS MOVED HERE THANKS TO VIRGINMEDIA REMOVING ALL USER WEB SPACES***

https://www.dropbox.com/s/q6q4y8rn37ym8 ... 1.jpg?dl=0

Template for the tank walls





Folding the tank walls.





Not a bad initial fit.



and better after some filing and grinding.





So I cut the hole out and marked for bend-tabs. The tabs prevent the edges burning -back when welding. The tank acts as a huge sink so you need a lot of power to get going but less as the tank heats up. With no foot-pedal on my welder I was battling for a good compromise on the initial one. Bending the inside edge up helped a lot with both fit-up and welding.



Started welding, inside and out.







Template for the lid.





Bending the radius in the lid. No fancy tools just a piece of round bar and hand-bend around it.



Welding the lid on.





Two pin-holes and a leaky seam. I tried really hard to weld that seam up air-tight from inside but even after close checking with a mirror it still leaked a bit.



So I made a fillet-piece and welded that in. No more leaks, plus I drilled a couple of holes in the wall first so if would also hold that bit more fuel. This was even more awkward than welding the inside joint using a mirror. It was hard to keep the arc in the right place with such a tight gap.







Last pic to show the ECU mounted flat. There's a small gap between the bottom of the tank and the ECU so they don't touch.

https://www.dropbox.com/s/h8k9qosjqlps479/ecu.jpg?dl=0

Very impressive.

f90x wrote:Very impressive.

+1!

Mike

You're being a bit hard on yourself - that looks like a good job.

Al

Very good!! Now why didn't BMW do that?

Thanks a lot guys

I read somewhere that the loom has to be extended to place the ABS box at the front of the bike, but I didn't find that, I just pulled that bit of the loom out and found that it reached perfectly fine, so the ABS control unit is now mounted to the horn bracket on a little plate. The ECU brackets are just the arms that normally hold it cut off and welded horizontally to the battery tray.

Nice work! I reckon you could make a few quid selling these. Plenty of old tanks for sale, and you could even do it on an exchange basis. I'd welcome the ability to be able to ride more than 135 miles before the light comes on.

Pete,

superb work. If I remember correctly bigger tanks have been tried before but the accepted wisdom was that it only worked on non-ABS bikes because of the placement of the ABS module below the tank. So, it looks like you have taken development into a new era !

I second Nik's suggestion that there will be a number of people keen on a longer range

Just to be clear, it's only the little electric box from the ABS that I have placed on the horn bracket. My bike had the ABS removed by the previous owner.

I'll be honest with you guys, I couldn't do these fast enough to warrant doing it for money, I'd earn only a fraction of what I'd make just going to work and doing overtime (of which there is no shortage) and I generally work long hours and weekends anyway so time is very much at a premium.
That said, I now have a spare tank (the original) that I planned to do in order to recoup some of the money I spent on the ones I bought (and the half a bottle of argon I've used) rather than just have it sat knocking around so if any members are truly interested in buying it I suppose it would be just as well if it went to a forum member - but I don't want it to seem like I'm using the forum as an outlet. My prime motivation now is welding practice, the second tank is already a good bit better than the first but the argon is expensive so if I could cover my consumables AND get good welding practice in then it would seem worthwhile to do a couple on an exchange basis.

Motocod if your tank is unmodified and you are putting the light on at 135 miles now then you'd be getting to about 170-180 with this tank at a guess and a range to empty of about 215-225 miles. I get less (about 205 to empty) because my riding is all filtering in heavy traffic or stop-start city streets and I'm a bit heavy on the throttle when it's time to go.

My bike has no abs anyway, so space there isn't an issue for me! Typically when I fill up its at about 140-150 miles, and I tend to be putting in between 14.5 to 15 litres in. Standard is 18 I believe?

Have a think about what you'd want to charge - I could source you a s/h tank...

Nik

I do believe 18 litres is quoted. I took that black plastic thing out of my tank, bent the breather pipe right up to touching the top and drilled the neck of the filler and I could just about squeeze 19 litres in. This would get me three days commuting but it was cutting it too fine for comfort, hence my re-working the tank for more capacity.

Ja , very neat job you've done there .

The small tank is a hassle , with me as well , 2 days commute then back to fuel up again ....

Pete,

Niiice.

What welding kit do you use, and is the aluminium a particular grade?

Regards
Mark

Cheers but I've got a long way to go. I'm just doing a third tank and it's an improvement on the second.
My welder is an old transformer-based AC/DC tig unit, it's visible in one of the photos. It has HF start but no other fancy controls apart from amps and gas flow. Might seem a bit masochistic learning on such a basic machine when there are so many features on modern plant to make life easy but it's solidly reliable industrial machine and besides I got it for a song.
The ally is 2mm sheet. I think it's 5052, we use it at work to repair machine guarding. It's 30% thicker than the tank's alloy which is about 1.5mm thick (but varies a bit, it's thinner on tight curves where it's flowed when stamped and you have to be careful not to burn through). The tank's ally is quite a soft grade too I suspect it's 100 or 300 grade.

I must confess to having some trepidation about working on the fuel tank but that was proved unfounded by my mistake with the pressure-testing on the first tank. Despite being stretched and expanded hugely out of shape the only place it failed was a 15mm hair-line crack on one of the factory weld seams.

You've GOT to post a picture of that!!!