Make your own Alloy Fuel tank.

A page for you that think you may be able to make your own Alloy trials tank or even, finish a kit off, by welding some of the parts.


We will investigate the methods and what is available and what you might need in the way of tools.




 A Classic-Trials Fuel tank kit on Faber "Otter Mk 3," Frame.



A tank like this? or one with a better shape to fit the bike?



Just look at this video for a start and you will see that you don't have to have a fully fitted workshop to make something that not only is a work of art but quite beautiful too, and trials tanks can be the same if you try.




Tank Kit later.




Now you can make something like this, the tank on my "Foster Otter" that was built totally old school.

And we have the construction methods of this tank documented.


Photo Courtesy Classic-Trial.


Photo Courtesy Classic-trial


Photo Courtesy Classic-trial.



A Classic trial teardrop tank kit ready for welding, all you need is a filler cap, which we will show you where to get one from, or make a boss on the lathe. also the same with the Tap -Pet-cock outlet..

Kits are available if you email me at

I will pass you onto the maker...



Or something like this new kit  that we will be building.



I also have pressings for the original Wassell tank that has been used for years on Triumph cubs etc, and I will be also finishing this tank and trying to build a BSA B50 replica tank. so this page should become interesting. for you.

We will delve into the methods, and welding techniques, for both Gas and tig welding of these tanks, and what you need to do to the aluminium to be able to work with the material.



B50 style 




"Slim Jeff "tank. BSA B50



You can see that with a bit of patience and perseverance. you could get artistic with your fuel tank 

 and spend many happy hours in the shed, creating a masterpiece.


More Later and this page will build with the tanks. 


Other bits you will need to complete your tank are a fixing tunnel or other brackets to hold the tank, alloy tap bosses to weld in and a sleeve to take a filler cap press fit or screw,Oh and also a breather pipe it the cap does not breath.



The through tank fitting tube of 2mm thickness is at the back of the group.




This simple CNC'd cap is available at a very good price, but you will need to weld in a vent pipe with this type of cap.

And make sure the neck to weld on is at least 2 mm thick.



This is probably the best 2" to buy, at a cost of £20.

You can weld a tube from inside the neck and down through the tank venting through the bottom for a neater method, of venting. 


You can if you like, aluminium braze this filler and the tap, like some of the old manufacturers used to do, the softer aluminium compound  with added zinc works a bit like solder.

The HT 2000 rods available are good for this, and worth a try.

Or turn a ridge on the bottom and weld it from the inside.


























A C15T type "Loaf" tank as fitted to the original framed C15t for replacement of the factory fitted steel tanks,these were made by "Lyta"

who Made all the alloy tanks for the BSA factory, these are  now copied by companies in India, but I have not seen one close up, but told they are OK, but the shipping cost to Britain seems to spoil the value.



Now fixing the tank to the frame can be a problem.

You can like BSA-Triumph seemed to do have a through tube made from 2mm thick tube and use a expansion rubber bush to hold it.or weld in an alloy washer if you want to suffer from vibration cracks. An alloy tank needs to be fully rubber mounted... or you will get problems.. I will cover this further down the page... 


Or you could go for a system similar to this Beamish type tank and use to frame side mounting rubber bushes at the front and a fixing at the back, I would go for a bungee over a alloy hook bracket? Why ? well you can see that the bolt bracket on this tank as again suffered from vibration and as had to be welded back on and some juncture.



The only problem with this fitting on a "Otter" type frame is that you need the tunnel very wide.



Front "U"bends tacked on to the sides of the tunnel.



For a "Otter" tank you need at least 2" between the bends,to fit it over the top tube.





TLR tank to where we have got too...


Sat here still with no road closed at the IOM for the TT, at 10 thirty on the first of June. Thought I would update you on progress with the alloy tank production…

I have spent another eight hours on the little TLR tank…

I pressed the tunnel up last weekend and that turned out real good, I would be lost without our old folder and fly press, they just make life easier…

But you still have to use your head to the best way to approach what you are doing.

Well after getting the shape near to what I needed, with the use of a right and left hand pair of tin-snips, and the old band saw. I was ready, to tack in the base… firstly I welded the two front-angled joints so to make the base a bit more rigid…

The tacking and welding of the base went quite well, so I stopped there for the day.. And took the tank home for inspection, and to send Chris off the photos I had taken… He mailed back saying perhaps I should turn the power up a tad..

Anyway I worked out how to bring the front and back together, for the next days attempt. Firstly I cut the small back infill section, and this did turn out to be tricky to get right.

Then I made a tool to put a small flange on the front sections, as I thought that was the best way to get a good strong joint, with no distortion. So the welder was switched on again and the back tricky little section was tacked in, and went better than expected. But, I could not get the weld alloy to run into the sharp two corners. I was worried that if I turned up the power I may ruin the tank.

I then turned to the front and tacked the section joints together, and then on a roll welded them.

I was pleased with the days work and left it there.

I could not fit the tank top filler neck as I had used it on one of brother’s Ariel oil tanks so had to order another.

I then on the lathe turned up the two link tube bosses. And drilled them…

Go on weld them on I thought (and this is before I made the third hands? Later) the first I perched onto the tank and managed to tack and weld it stood up over the top of the tank…The second I managed to tack one side but them melted it through and It dropped off, Bu***r..

So back to the lathe and turn up another, this time I only drilled it half way, so as to leave the tank side section solid. That worked and I welded number two on. Taking the tank home again I decided to fill it with water to see what capacity it was.. That was fine but the three pints ran out of the back corners of the tank rapidly and there was a pinhole in one of the bottom runs, photos off to Chris again…

Turn the power up and stand the tank up in the air to weld the corners, I had suggested to him that I might even alloy solder the corners so not as to spoil the tank, NO he said don’t do it, weld them.

So I get over the workshop, with a bit more confidence and turned the power up more on the welder… It worked and I got the corners, and then re ran the bottom and some side seams. Much better. Just waiting for the tank top now. And shall I fit a tap boss or fit an inline tap?

Chris sent me a video link for making Third hand welding holders so the next two, no sorry three days I made four, and one very special to hold the   Foster frame oil filler neck in place while bronze welding that…


 Good progress Day two.



Getting there.



"Third Hand" welding  clamps with bronze welded feet ends to eliminate ark-ing.



Clever little clucker's



TLR tank now finished...



On the 27/06/2019, I finished the little TLR alloy tank, by first making tooling for the fly-press to punch the hole for the filler cap in a sheet of 2mm alloy , this was the best way to do the job so that the inwardly swagged hole left a simple job to weld the bought in filler neck around the inside , so leaving a neat finish around the top of the neck..

Tooling was a piece of the correct size thick wall tubing bored out slightly, and a ball ended draw-bar pin of the right size. this swagged and cut a disc for the neck out in one pressing.

I then drew the shape I needed around the punched hole and cut it out on the band-saw.

With the neck firstly welded it was then a simple job to weld the assembly onto the top of the tank..




 The glass-fibre cover  will hold the tank in place on the frame, so no fixings were necessary... and I have decided on an in-line tap ( pet-cock) as the tank hardly has room for another fitting...


 So next week 11/08/2019... I will start on welding up the BSA tear-drop tank...




Right Vibration and Resonating cracking of alloy fabricated tanks as I see it...

I have just been reading that some of the top class made alloy tear-drop tanks fitted to Drayton Bantams have been cracking along the top front seam of the tank.

As I have said earlier aluminium tanks must be fully rubber mounted and isolated from the steel frame they are mounted too.

So lets take a look at what might be causing the problem...

Think of a musical instrument...  Drum, trombone, even a tuning fork...

 If you strike this on your bench or even drop a eating fork onto the table one with long prongs are the best.

 See what happens there is the initial  bang as it hits the table but then noise resonates from the fork for quite a while. Now do the same thing with a microphone linked to a speaker ( my bass amp is the best.) Now touch the top of the cab as they are named and feel the vibration coming from this that keeps on going...

OK you now have that in your head.

Well your aluminium tank is like this bass amp... and the vibration and sound from your engine (if the tank is not fully isolated from rest of the bike) is taking in all of this movement and sound. And although you can't see this, the movement is work hardening the alloy as they say, and the already hardened part through welding will  show up first as a crack. ( just stand on an empty Coke can and then try and bend it in half, don't take long does it!)...

The biggest culprit on these tear-drop tanks, is the shape , they look good I love them, but the line of the tank follows closely to the line of the frame top tube...

 And this means there is no lateral shape in the tanks like for instance the BSA "Loaf" tank... It is this shape that strengthens  the structure and dissipates the  vibration and sound better ...

The two fuel carrying parts of the tank are like the hollow part of your acoustic guitar..

 And if not that full of fuel will act the same, and vibrate with the movement and sound.

 This then is transmitted to the weakest work hardened point, the top at the front of the tank...

The manufactures have now tried to  eliminate some of this movement  by fitting a bracing bar between the two sides of the tank at the bottom...

This should help in stopping some of the  bass vibration  but the tank will still receive , the high frequency vibration if anything from the frame is touching the tank.

A two-stroke like the Bantam engine is always going to vibrate more than a four-stroke, and they were not very balanced in the first place and do suffer with vibration, even the original steel tanks used to crack...

So if you want to look after your investment, and the tanks are not cheap.

Make a point of mounting them on vibration proof material as best as you can, the more effort put into the mounting, the more chance you have of the tank surviving a lot better...




I am just about to weld up a batch of three Ariel tanks, I have the top skins and now I need to cut up and weld the two mm bottom sections, there is two ways of doing this, make a wooden "buck" and try and form the complicated under tank or make it up in sections.

 I have the glass-fibre mould for a Ariel tank and I am thinking if I moulded an underside section and then filled this full of resin I would have something to work the alloy too? We will see...








More later Tank you.