Removed the tank and the tap, tried plumbers tape with no success. Noticed that a seal is actually formed (or supposed to be formed) by a severely perished rubber gasket between the tap and the tank outlet. Drove down to Repco and grabbed a suitably sized O-Ring. No Joy. Gas still coming out, but now it's positively hosing out. GRRRR.
With finger over outlet, pull tank over. Gas comes out! AAARGH. Take out 20X eyepiece and inspect: found a 2.5cm fracture around the base of the outlet. Panic Time!
Called the guys who maintain my 928 about who can weld a gas tank on Monday. Glyn told me to sand down the fracture area, clean it up nicely, and use JB WELD on it.
Sanded, roughened, and cleaned with Lacquer Thinner (IPA also acceptable).
Mix and apply JB WELD to the fracture line, about 2mm thick.
Wait 15 hours. Put finger in outlet, tip tank over. No leak!
Re-fit tap (no plumbers tape) and re-fit to bike.
LEAK GONE.
http://www.jbweld.net/products/jbweld.php <-- Frikin' Awesome!
