You need a shop manual(if you dont have one) check your timing and check your heat riser under the carb, you need heat at the base of the carb to keep it from freezing up. Cold air, cold fuel=rough running, so make sure the base of the carb is hot and not cold or ice at the base of the carb. BTW get a propane torch, turn it on do not lite it and use it to check for leaks, much safer this way. Have fun
