Also take the plug that is firing and hook it to the other plug wire and ground that plug against the bike. Crank the engine and see if you get a spark. If you do it may be a simple matter of replacing the plugs and adjusting the carb/fixing the float if it is stuck.

I learned all I need to know about life by killing smart people and eating their brains.
Eat right ,Exercise ,Stay fit, Die Anyway!