So I purchased my brother's old XR100 back from Jimmy. He told me it had a gas tank leak.

I took it off tonight and the leak is a rust spot from the bottom seam on the tank. Any ideas on how to repair it? I have 3 thoughts:

1) Properly flush the tank, i.e. no gas in it, put water in and out several times, run air through it for a day. Then try to lay a bead of weld over the rust hole. I think this would be very hard because the metal is already thin, but add in the rust, makes it way thin

2) Properly flush the tank like above, make a small patch piece and weld it over like a scab. Advantage here is I might be able to get to better metal, disadvantage is I will create a little pocket in the tank

3) Some kind of epoxy? any suggestions? JB Weld, Do you guys think it would hold? It would suck to be out somewhere and be stranded cause the tank ruptured, spilled gas on me and the bike, then caught me and the bike on fire....

Thoughts? Anyone got experience with this?