I have x2 247 Cotas that I'm restoring.

1 has the original glass fibre inbuilt tanks and the other an aluminium tank that sits on the frame spine with the fibreglass tank internals removed.

What is the UK situation with running fibreglass fuel tanks as I believe back in the day they were banned hence why some bikes have ally ones?

Thanks Folks

 

No problems with fibre glass tanks in non road events so long they are not leaking

26 minutes ago, teamferret said:

No problems with fibre glass tanks in non road events so long they are not leaking

OK - Thank you.  I think the fibreglass tank is a neater solution assuming it's done well.

I am reasonably sure you are okay these days with a Fibre glass tank being used on the road 

As far as i can recall , there was a law requiring metal petrol tanks in the 1970s / 1980s ? 

But that law has been removed a long time ago 

I could be wrong , and if I am then someone will surely correct me - but there are plenty of  modern cars & modern Enduro / Trials bikes that are road legal , with plastic tanks 

There is some issue with fumes leaking through the fibreglass. I resprayed the tank on my 348 and the paint began to bubble once filled with petrol. There are suggestions are that modern bio fuels can soften fibreglass, in USA lots of petrol powered boats have GRP petrol tanks and its become a thing for them too.

They are rare but the alloy tank is easier to look after. if buying unseen bear in mind some alloy tanks are not a good fit in some  covers . I had a few and it took some swapping to find a pair that were a good fit.

Plastic fuel tanks are quite different, tested approved and not so likely to crack as 40 year old fibreglass.

I had a Buell the plastic fuel cell on that has a decorative cover .I have a 'modern' triumph with a plastic petrol tank. These are reportedly changing shape with modern petrol, Mine has become a tight fit in the frame but again its 23 years old.

My fiberglass bultaco sherpa tank kept sending the fuel a rusty orangey yellow, so iv cut the bottom off to use as a shroud and brought a small cheap metal tank to go underneath its not perfect I don't care. 

Just wait for the mandatory unleaded E10 to be available in UK, later in 2021

 

The ethanol will eat through fibreglass and a lot of plastic tanks then

Good points about the problems you may have with modern fuel in a Fibreglass tank { or a plastic one }, using an alloy tank has to be preferable to avoid any problems

going back to the original question about fibreglass tanks being banned {for road use} - I think the law was that a tank had to be metal , so this obviously excluded fibreglass & plastic of any kind, but I don't think this law lasted long as I know some BSA road bikes had fibreglass tanks in the late 1960s , and There are some 1980s road bikes with plastic tanks , it must have been a short lived 1970s law that got removed 

 

Thanks folks & some good points raised.

I've road bikes with plastic tanks and have had many enduro bikes with plastic tanks too.

I was planning to line the fibreglass tanks with something.

Where could I find a basic ally tank to sit under the shroud?

I was more concerned that my freshly renovated trials bike wouldn't be allowed to trial if the tank was banned, but looks like that's OK now.

6 hours ago, Marky16 said:

Thanks folks & some good points raised.

I've road bikes with plastic tanks and have had many enduro bikes with plastic tanks too.

I was planning to line the fibreglass tanks with something.

Where could I find a basic ally tank to sit under the shroud?

I was more concerned that my freshly renovated trials bike wouldn't be allowed to trial if the tank was banned, but looks like that's OK now.

You won't get turned away from any trial for having a fibreglass tank. There are new fibreglass tanks still being made and being used on plenty of bikes 

The law was introduced in 1973 following a road accident when a fibreglass tank spit and caused a fire. Hence all UK trials bikes had an alloy tank from then on to replace the original factory glass tank. It's never been clear as to whether the law was for all bikes or just those registered for the road, but as most trials were road based back then I think they all had their tanks swapped for alloy versions at import. It only applied to fibreglass tanks, doubtful there were any plastic tanks at that time. 1980s bikes were used on the road with their original plastic tanks

On 3/5/2021 at 6:18 PM, woody said:

You won't get turned away from any trial for having a fibreglass tank. There are new fibreglass tanks still being made and being used on plenty of bikes 

The law was introduced in 1973 following a road accident when a fibreglass tank spit and caused a fire. Hence all UK trials bikes had an alloy tank from then on to replace the original factory glass tank. It's never been clear as to whether the law was for all bikes or just those registered for the road, but as most trials were road based back then I think they all had their tanks swapped for alloy versions at import. It only applied to fibreglass tanks, doubtful there were any plastic tanks at that time. 1980s bikes were used on the road with their original plastic tanks

Thanks for the info.

I've decided to keep one bike with the fibreglass tank as it has now and the other with the Ally tank..

As has been said above, its not going to be the use of a f/glass tank at a twinshock trial, but rathermore the E5 and E10 ethanol containing fuels that will be effectively be 'eating' and destroying the fibreglass. (Along with fuel lines, plastic carb floats, rubber tipped and plastic float needles).

Its a well documented fact.