Britbike forum Forums British Motorcycle specific Brands Bsa bulletin board Leaky 66 Spitfire tank

I have a nice fiberglass tank on my bike that i bought last year that leaked gas a bit at a seam. I took it off the bike and resealed the inside with Caswell tank sealer . The sealer did the job but now the tank is leaking at the main petcock . It's 5/8" - 16 mm OD that screws directly into the threaded insert of the tank. It had a lot of sealant around it when I took it off to do the tank seal but neither petcock was leaking when I originally added gas to the tank ( it came dry when purchased ) . The threaded insert in the tank was questionable, threads are glazed over and there was a alot of sealant around it . I did the best I could to clean it up and used Permatex 85420 gasket / sealant when reinstalling the petcocks. The reserve petcock has an adapter screwed into the tank with a small petcock 3/8" - 9 mm OD and the gas just trickles out of it . Both petcocks are very hard to operate.
I 'd like to have new adapters installed in the tank with new 1/4" petcocks.
Does anyone know of a place in southern Ca. that could do the work ? Or even if i have to have it shipped somewhere else. I've never done it and would prefer to have a professional do it. I'm in San Diego.
Any referrals or instructions in how to do it myself if it would come to that is appreciated also.
THANKS

There are a lot of entries on this site about "fixing" fiberglass tanks. It looks to me like there are NO "permanent fixes" for what was junk to begin with.
Some countries will not allow fiberglass tanks on motorcycles. I have been told by my Canadian friends that Canada is one of those countries.

You are working with a sub-standard material that is now over 50 years old. It's a type of resin plastic material, with fiber strands mixed in it.
Plastics have a life-span. Sunlight causes some deterioration, and modern fuels causes even more. These tanks have out-lived their intended life span.

I saw fiberglass boats in the late 1950s begin to have soft, mushy bottoms after only two or three years of use. Any fiberglass item that is in or near
petro chemicals will experience some bonding deterioration. This is what you can expect of fiberglass, especially OLD fiberglass.

Buy a steel or aluminum replacement tank, and be done with it.

I disagree. Your points are well taken and your alternatives are correct. But if you want a glass tank one must be mindful of its fragility.
Care of an archaic polyester resin fuel tank by correct lining with Caswel, Por 15 or Bill Hirsh products and draining the tank dry
Leave the cap open after use is how it’s recommended. The other thing is you can buy good race gas. Time after time I see guys glass tanks fail at the seam because they left fuel in it.
I’m not sure I understand the leaky pet cock threads. I use a rubber cork to plug the threaded hole.
I know these are difficult to deal with.

i have a 70 Commando with a fibreglas tank. i use nothing but non-ethanol fuel in it and live with short range limitations.

when i go anywhere that requires a fillup other than my local non-ethanol supplirr, i take another machine

if i was planning on anything long range with this 53 year old bike, id buy a tank from india and set the glas tank on a shelf for the next generation.

What kevin said......

A bunch of years ago when the ethanol was only 5%, my resurrected "66 Spitfire started leaking at the seams. I tried Caswells but it didn't work for me. I took it to a local fiberglass guru. He cut the bottom off at the seams, chipped all the crud out, and painted a thin coat of Caswells on. Fiberglassed the bottom an d poured Caswells along the seam with a tube. Worked great. His theory was that you want as thin as possible a coating because the coating and the original fiberglass have different modulus of elasticity and over time a thicker coat is much more likely to separate. Anyway, they increased ethanol to 10%, I figured it was only a matter of time before my tank became unuseable, so I bought an unpainted metal Indian tank. It required some minor work to work properly, but now it looks fine and works. It looks pretty original. If I put my original tank next to it, I can see some minor differences, but unless you have the original right there they look the same.

Ed from NJ

Thanks all for your input, albeit it's not what i wanted to hear. The bike really looks good with the 2 gallon tank as the paint is in very good shape and really compliments the bike! In a past post that i sent I took everone's advise and purchased a new 2 gallon aluminum alloy tank from Holtworks and have a local source for 110 Octane leaded fuel . I realized the short range I would have to adhere to not buying the 5 gallon , 80 - 90 miles ?, but i don't like the look and I do have other bikes for longer distances.
However I still have a problem even with the new Holtworks tank as they welded on the petcock ports to the bottom of the tank , 9/16" tall, which drops the petcocks lower than before. The frame & engine on the bike are not in alignment resulting in one petcock 7/16" away from the rocker cover on one side and barely 1/8" on the other . I question the long term issues with this what with vibration, function etc. Michelle @ Holtworks is working with me on 90 degree spigots etc. and i'm thinking of shaving the two tank mounting rubbers to see if i can align the tank with the motor.
It's funny, the bike is like brand new. I purcashed it from an 80 year old guy who was a BSA, Triumph , and other bike dealer in New Mexico last July.It was one of many in his collection. The bike came with the 1st place AMCA trophy it won in Las Vegas in 2002. He had it in a climate controlled building for the last 20 years only driving it a couple times for 35 total miles ! He supplied a video of it starting and bring driven . I changed all the fluids in the bike put on new tires etc. and 7 months latter I haven't even ridden it! LOL

Pictures of this bike are definitely in order and even the video if you have the know-how.

Pollyester resin has a finite life span
It will start to split at the seams then the petrol wicks up the strands and eventually the whole bottom of the tank turns to mush
Your might be good now and you might get a few years out of it by installing a linner PROPERLY ( most don't do it properly ) but ultimately it is an ornament .
SO either get replica made in epoxy resin which is more resistant to chemical attack or get one made in steel or alloy
painted the same it will look the same but at least you will be able to ride the bike with some lvel of confidence that you will come home on it not with it on th back of a truck, or even worse , leaking fuel setting fire to the bike

There is a company in Spalding UK that markets a tank sealer

https://www.rust.co.uk/product/cat/...vehicle-restoration/sealing-a-fuel-tank/

I believe it's also used on boats that have glassfibre fuel tanks.

Just be aware any solution is only good for todays petrol (which changes with the seasons anyway), any future changes may affect a product that works today. So steel/alloy is more future proof than a lining.