PURPOSE: To provide a device which is devised to improve the starting device of a slide throttle valve type carburetor and improve acceleration operation after deceleration.
CONSTITUTION: A starting valve 28 comprises a regulation shaft 29: and a needle valve 30 for starting and movably arranged in a starting valve guide cylinder 21, and the regulation shaft is extended through a holder member 32 to close the opening of a starting valve guide cylinder 21. The starting valve is vertically moved and regulated through forward and backward movement of a regulation member V. In the lowest opening position of the starting valve, a needle valve large part 30A for starting is inserted in a regulated state in a fuel nozzle 24 for starting and fuel draft is suppressed. During idling, a slide throttle valve 13 is held in a fully closed state and air for idling is fed through an air-fuel mixture passage 23 for starting and fuel for idling is fed through a pilot outlet hole 11. Further, during deceleration, the occurrence of adhesion on the inner wall of an intake air passage 2A and residence of fuel is suppressed by blow-off air from the air-fuel mixture passage for starting and following acceleration operation is improved.