I have a "classic" japanese motorbike which has been recovered from a
damp barn after 10 years.

Main obvious problem was the fuel tap had been left on and the carb
float needles gummed shut. Having part filled it with fuel, taken it
for MOT and failed on rusty fork stanchions and sticky brakes which I
have fixed I now find two small petrol leaks from the fuel tank.

Someone has plainly tried to fix this in the past as there is lots of
what looks like polyester resin littering the tank. I have shaken an
old chain about to break up most of the plastic but it precludes
attempting a repair from inside with the likes of POR15.

So I have decided to attempt to solder a repair and then float a piece
of brass or copper plate over the repairs.

I don't want to use a flame to avoid damaging the paint work or
distortion, does anyone think a 400W electric soldering iron will have
enough power? I ask because I will have to buy one or a big lump of
copper to heat up.

Any other tips, like what solder (I have some old 60/40) or flux might
be best.

AJH