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Bikes: all ducatis except for one prewar Beemer
Posts: 7
Join Date: Sep 2009
The problem has been well sussed.
PA6 - the material that the tanks are made from -- absorbs water.
That's pretty much it.
There is no inner liner of the tank, so it is in direct contact with the fuel. Gasoline often has water and sitting atop the engine means the heat creates a nice environment for condensate when it's cooling down.
Add ethanol to your fuel and you learn that it absorbs ambient humidity 10-20x faster than pure gasoline and holds more (E10 holds up to 1% water by volume, whereas pure gasoline only holds about 0.2% water by volume).
Coating the tanks absolutely works and there are many different epoxy based preparations that have been around for a long time. PA6 (aka "Nylon 6" or "polyamide 6") was invented in 1938 so its properties are well known.
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