LOOKING FOR A LEAK IN A GAS TANK

[RB]

[scootsx2]

Try silver solder. Higher melting point than tin/lead solder and harder alloy. It will flow well if the surface is clean and you use appropriate flux.

I would flush the tank out several times with a soapy solution followed by clear water and then let dry. You can use a vacuum cleaner's exhaust to force air through the tank interior to help it dry and ventilate. When I did the tank on my '56 Francis Barnett I did a final rinse with acetone and let that air dry overnight before silver soldering.

If you want to be really safe then take the tank to a radiator shop that also does fuel tanks. That's the approach I used with my CX500 trike.