What guage are khi tanks made from.

[warren3200gt]

As title guys, what guage steel are khi fuel tanks made from. Need to get radical with a poorly J tank and want to get some new sheet before I start cutting.

[Al]

J tanks are around 0.75 to approx. 0.8mm or so depending on where you are talking about specifically. The material behaves like modern 'high tensile' which is next to impossible to weld successfully. Modern 'sheet' steel that you buy, borrow, snaffle is ductile and maleable by comparison and makes a poor match for compatability when sharing carbon content and other traces like silica etc. and usually results in the parent metal splitting 'around' or 'radiating out' from the weld after cooling or grinding back.
Where has it gone? Bottom edge or round the badge fixings? There are very different approaches for different locations ~ example, bottom edge pin holes you punch in with a centre punch to make a dimple, then silver solder / braze into the hollow and file back afterwards. This leaves a 'rivett' of repair metal below the surface. Same thing approx. for round the badge fixings except you can 'lead wipe' them with 'solder paste' to seal them fully. 'Lead loading' either afterwards is not usually sucessful because lead loading will almost always contain pin holes full of flux and tallow!!!
AL

[warren3200gt]

Thanks Al, I'm gonna have to cut out a section below the badge area. It's on a tank which came with a parts bike. I eventually sourced a replacement tank but knowing the rarity of J tanks and having nowt else to do I thought I'd have a crack at repairing this one then lining it. There are also several other small dents on the same side and if I cut out someone's "attempt" at dent removal I could the get inside with a dolly before welding a new panel back in.
If needs be I could get the cut panel back into proper shape before welding it back in.

[Al]

Someone has done that through the fuel level sender hole with a broom handle or more likely a tyre lever!
The problem there is that they have stretched the very hard (brittle) metal and it would be a lucky man who could heat shrink that back and not crack it.
Panel beating that 'cold' would just 'work harden' it further and without shrinking it you will end up with it being too 'full'.
If you cut it out and flatten it you run the risk of many small hairline cracks and will almost certainly grind through it on clean up!
TIG welding like gas welding will cause it to swell and the weld 'fixes' it in the swolen position; too 'full' again.
MIG welding will leave extra material on the inside to prevent you grinding through and leaving it transparent to liquids but MIG shrinks on cooling and will possibly turn it inside out requiring you to stretch it afterwards! That cant be done if there are gobs and strands of MIG on the inside as there will be!
Any of the above and you will immediately be transported to another universe of pain and regret!
I hate to say it but if that is not perforated i would do anything possible to avoid cutting as it soon will be.
I have just adressed something similar on mine after a tumble at Snetterton (and a previous one at Cadwell) and used a push rod (wooden round ended broom handle) through the sender hole to push up on the 'lows' and tap down on the 'highs'
AL

[warren3200gt]

There's a company just round the corner from me that specialises in welding repairs to high pressure mainly food manufacturing pipe and tank repairs.
I might get some advice from them as they weld repair every imaginable shape. Not sure they have any experience on tanks though. Anything I should be telling em?

[Al]

Cant think of anything in particular except to ask them to point you in the direction of a suitable dye penetrant test liquid.
You normally paint it on the inside and watch for blooms on the outside for pin holes and cracks. It comes as a 'paint on' or 'spray on' and they may let you have some.
Something like this. There are many.
https://norsemensafety.co.uk/product/ma ... gJ34vD_BwE

Lead solder 'Tinning' paste if you havnt come across it before.
https://www.frost.co.uk/solder-paste-20 ... gJXFfD_BwE

I sealed my J tank about seven years back with the POR15 three stage process and managed not to damage any of the painted outside. Not had any problems since thankfully.
3rd stage (finish coat) is basically Hammerite and what i emptied out of the tank i used to paint an engine stand, a cycliner head stand and a few other bits 'till it was used up .
AL

[warren3200gt]

OK, thanks Al,
Waste not want not. Ex northerner by any chance.?

[Al]

No one knows who my father was so any things' possible.
AL

[Z1streetfighter71]

To save a bit a hassle, i spotted this last night, if you know a bit of German.....
https://www.ebay-kleinanzeigen.de/s-anz ... -306-10552

d11867af-d258-44c6-a60e-ff0bba55fa02.jpg (88.36 KiB) Viewed 1724 times

[warren3200gt]

Good spot and cheap for J style tank. I would also need a tap to fit that as my (now spare) tank is 2 bolt type.
Mine is now stripped awaiting for any fuel vapour to deminish then fill with co2 and get a slitting disc to it.
The guys I spoke to just laughed and said good luck.
A mate has made alloy race tanks for 40 odd years but don't know how good he is with steel so he's the next port of call over the weekend.

[moizeau]

Warren, regarding neutralising the vapours inside the tank.Connect a pipe from the exhaust of a petrol car and put the other end in the tank. We did this at Norton years ago to bikes that were going on a plane. Not sure of the timescale though but I remember them sitting like this for quite a while.

[warren3200gt]

Thanks Pete, I've got some blanking plates for the guage and tap. I'll fit them and fill the tank with water and do the cutting. Once I have a kin great hole in the side drying the tank out will be simple.

[BAFF1960]

Hi.
Have you considered removing the damage/rusty area and weld in a section from a similar tank [ cheap ] of the same era, ie 500/550/750. Not that hard to reshape flatish panels to suit.

Alan

[warren3200gt]

Metal shaping is not an issue for me, welding I'm not so hot on and not sure I would trust it after I had
Once I've spoken with my mate over the weekend I'll know which way I'll go with it. Alternatively I could just refill it with plod and throw some paint on it and become an ebay rip off artist

[Al]

https://www.youtube.com/watch?v=aq1yV7P51yU
AL