Fiberglass gas tank

has anyone ever attempted to build their on fiberglass gas tank?

No, but consider that now with the high alcohol content in the gas here in the U.S. building a fiberglass tank might be somewhat dangerous.

I've read about the large yachting perople having trouble with their tanks made of fiberglass,some have to almost dis-assemble the yacht to get the tank replaced.

I understand that the gas/alcohol mix will attack the adhesive holding the tank together. I suppose if you seal it, it might work.

Maybe POR-15 or Kreem might work, but again, there's still solvents in the sealers that might make this unworkable.

There are definitely sealers for fiberglass tanks, find the right one, make your tank. The biggest problem is that they're not great for road use. Steel tanks deform in a crash, whereas fiberglass will shatter, all the gas will be everywhere, and you could get hurt pretty badly by the shards.

You can use epoxy glass instead of ester and glass and use a rubber coating on the inside to prevent the shattering. I just never liked the idea of a glass tank sitting right on top of my engine. The glass tank holds heat and the gas will stay hot inside for a long time unlike in a metal tank.

wow.....you guys just scared the crap out of me. i guess i wanted to redo my gas tank to fit my bike better than my metal one...plus if I did lay the bike over..I wouldn
t jack up the original tank.

flat trackers use fiberglass fuel tanks all the time as long as its coated it should hold up to the fuel if you would like to check out a few tanks try omar's dirt tracking or phil little racing or airtech they build fuel tanks that are lined to prevent alcohol damage. also norton used a fiberglass tank on the 750 high rider so it definitly has been done before.

Airtech says this about their fiberglass tanks:

Please note! This gas tank is not recommended for street use, this is a fiberglass gas tank that will not dent. In the event of a crash, the gas tank may rupture and spill fuel possibly catching your motorcycle on fire. This gas tank is recommended for racing purposes, with racing fuel only!

Modern pump gas is pretty crappy stuff. It contains a load of oxygenizers, fuel injector cleaners, ethanol, ketones and other additives that can wreak havoc on a fiberglass tank. Even though we use a high-end aircraft quality vinylester sealer on all of our tanks, it is possible a reaction may occur between pump gas and the tank liner.
We therefore recommend that anyone planning on using pump gas in any of our tanks first coat the inside of the tank with a fuel tank liner like Kreem.