| 摘要 |
PURPOSE:To provide a variable venturi carburetor, in which arrangement is such that a suction piston is positioned to fully close the venturi portion at the time when engine is stopped, so as to increase vacuum at the time of cranking, and to open the venturi portion to a proper extent at the time of idling, whereby it is enabled to attain proper air-fuel ratio and to thereby render the engine operation stable. CONSTITUTION:Metering needle 33 is tapered at a designed angle from its base portion to the top and it is formed with small-sectioned portion 35 at such a position that spacing to metering jet 28 is increased at the time when engine is stopped, that is, in the state that head 16 of suction piston 13 is held in tight contact with bridge 32. The small-sectioned portion 35 is so formed to have a cross section smaller than that of the idling portion at the top of the needle. Thus, since venturi portion 5 is fully closed at the time of low-temperature cranking, vacuum can be developed positively in mixing chamber 6 at the time.
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