No, it´s not the outlet from the air cleaner chamber. The carbs are joined together by fuel and air tubes/pipes. There is one fuel tube outlet with a hose connecting it to the fuel petcock. There is also an outlet for an 8-9 mm hose in one of the air tubes, which connects the carbs together. This is located at the front of the carb assembly behind the radiator. What attaches to this outlet?