To provide an accelerating jet provided with a plurality of discharge holes which are excellent in mixture of air with fuel and high in carburetion efficiency through which the fuel is discharged in multi-direction, because of that since a double-barrel type 1 stage carburetor is conventionally manufactured for a racing purpose, top priority is given to a high output, low and middle speed drivability is ignored, but recently the carburetor is mounted on a general vehicle and it is in inclination to be widely used for circuit, response of a low medium speed and improvement of drivability are desired, an accelerating pump system being an auxiliary fuel is concerned greatly, and since the discharge hole of a pump jet is a single-hole large aperture, mixture of air and fuel is poor, and even if a proper amount is discharged, poor breathing (poor acceleration) and worsening of response are caused.

A conventional accelerating pump is taken out and exchanged for a pump jet formed in a proper discharge opening area and having a plurality of discharge holes through which discharge in a multi-direction is executed.