HEY that picture---its urine in that bottle you found not gas----if you go by a gas station they might have gastank stop leak putty.
or hang bottle from gas tank cap/neck,poke 2 holes in bottle cap,put line in one hole and run to carb,push primer button until gas reaches carb.start bike,if not starting prime again.hang bottle upright.
I'm so confident in this procedure of soldering a leaky motorcycle gas tank Matt I have no quirms what so ever about it. I'm speaking for me of course because I'm very meticulous when it comes to gas and fire.
I have no experience with any other type of gas tanks, large or small just the motorcycle tanks I've done. I wouldn't think twice about soldering one of these small tanks that come with the 49cc or 68.5cc kits. Piece of Cake!
Do know if Mopedman ever got it repaired?
RPM
Here ya go. This requres one dasani 1 litre water bottle or equivalent with a sturdy cap, A drill bit roughly the same size as your stock chinese fuel filter, and a few zip ties. Drill a hole in the cap, screw the filter/valve assembly in the cap with gasket, zip tie to frame. My water bottle got me to work for 3 weeks while I waited for a new tank.