First of all, what happened when the engine quit? Did you just go out to start it, and it wouldn't start? Check to see if you have compression on both cylinders. You say you are getting fuel to the carb, but are you getting fuel to the combustion chambers where it is lit? Try squirting a little fuel into the carb throat with the throttle opened up. Close the throttle and try to start the bike. Are you sure the plugs are OK? Are there any backfires thru the carb or exhaust?