Check that your carb is not leaking fuel internally past the needle/seat. Could be faulty O-ring around the needle/seat assembly, or dirt on the needle/seat, or a stck float not closing properly. Would typically make the engine run rough and smokey. If you have an electric fuel pump; try to shut it off while running the engine and listen to the engine if it smoothens out; this is simpler than dismantling. Or, you can look into the carb and see if gas is coming out of the maincircuits during idle (flooding)