When it comes to installing a new or even old gas tank on your bike there are two things you want to avoid, holes and excessive rust--you could spend hours if not days chasing down both. Holes or leaks are bad for obvious reasons. But even if your tank has no rust, if it isn't sealed properly, over time moisture can build up and cause rust and corrosion to develop which can then lead to rust flakes clogging your fuel line, filter or worse (getting into your engine and causing damage). Recently we came across a product that solved both these problems, and best of all it was quick and easy to seal our project tank.
MC Advantages offers the Stampede Fuel Tank Liner and unlike some tank sealers, which turn into hard vinyl materials that can chip and break off when banged or dented, the Stampede liner is a polymer that resists chemical and fuels and stays flexible when it dries, so it will expand and contract with the metal and doesn't crack. The liner has actually been used in the agricultural industry for many years to help restore old rusty tractor gas tanks. In fact that's where the Stampede Liner differs from most products. According to Stampede the polymer liner can be used to seal pin holes up to 1/32 of an inch, and as long as there is no loose rust in the tank, it can also be used to seal-in surface rust.
The tanks we we're working with were a set of split Sportster tanks that hold about 3.3 gallons of fuel. The tanks were fairly fresh and there wasn't a lot of rust built up, a few small surface spots but no flaking. We had already pressure tested the tanks and they were solid with no leaks.