To suppress deterioration of fuel economy or exhaust performance in the long-term use of a sliding throttle valve type carburetor.
The amount of fuel injection is adjusted by disposing a small venturi 4b in a suction passage 2, disposing a valve body 3 having a flat plate part 3a for opening and closing an opening thereof, disposing a tubular body 18 communicated with a main injection hole 17 in a fuel storing chamber 11a, inserting a needle-shaped member 16 into the tubular body, and displacing the needle-shaped member 16 by the rotation of a valve opening/closing input shaft 6 for opening and closing the valve body by external manipulation. In a narrow open valve state close to an idle state, a strong negative pressure can be generated against a fuel injection nozzle by opening only the small venturi, thereby improving fuel atomization performance in the narrow open valve state. Additionally, since a wall-shaped part of the valve body is slidingly contacted with the opening of the small venturi, there is no part allowing changes in gap during the valve opening/closing. Therefore, the part having a risk of abrasion due to engine vibrations or the like can be eliminated, and the initial performance on fuel economy, exhaust characteristics, or the like can be maintained over the long term.
AIHARA TAMIO
TAKANO ATSUSHI
SUZUKI HIROMICHI
SAKAGUCHI TAKESHI
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