platinumsmith said:
I stumbled into a garage sale the other day and made off with a '74 Commando for $500. It needed a battery and a few other things. I have a dude fixing it up. My question....It came with two tanks. Both are Roadster tanks. One is steel & the other fiberglass. Should I even mess with the fiberglass one?
It is quite possible to line a GRP tank to resist pretty much any commonly available fuel, without needing to take the tank apart (this is almost as much work as making a new one out of the appropriate materials!).
However the main problem is that most people are taken in by the blatant nonsense, thats suggested by those selling various epoxy resins to do this job.
The thing that makes epoxy sealants into a pretty short term remedy for sealing a GRP tank, is the film thickness of slosh coated epoxy is never uniform, and this linked to the difficulty of proper mechanical abrasion of the inside of the damaged tank and vibration, means that failure is likely to occur quite quickly on bikes which are ridden regularly.
When an epoxy sealed tank has failed its common that fuel will have seeped behind the epoxy coating adjacent to where cracks have occurred, and as well as rotting the polyester resin the tank was made of, this will mean that sealing the tank a second time will mean failure happens almost immediately.
There has been some investigation into the use of a modified polysulphide material for use as a tank sealant, but this is very costly and not something I would imagine is likely to appeal to sellers of the less than ideal epoxy products who are making around about 400% profit on repackaged industrial resins!
However while epoxy sealers are certainly a long way from being ideal, it is possible to improve the next to useless standard products by bulking them out with suitable filler materials such as chopped GRP fibres, which tends to make the thin film coating a lot more durable and less susceptible to cracking.
