| 摘要 |
PURPOSE:To improve acceleration characteristic when an engine is in warm operation, by using slow system fuel as the starting fuel to increase its amount only when the engine is started and jetting this increased amount of fuel through a bypass in accordance with the movement of a throttle valve when the engine is accelerated. CONSTITUTION:A carburetor has a slow system passage comprising a slow system jet 1, idle hole 4, slow system air passage 5, slow system mixture passage 7, etc. Here the carburetor provides the first passage opening and closing device 10 interposing in the half way of the slow system air passage 5. This opening and closing device 10 connects its negative pressure chamber 14 communicating with a manifold 11 in the downstream of a throttle valve 21 by a negative pressure passage 15, but the carburetor provides the second passage opening and closing device 16 interposing in between the said negative pressure passage 15. And the carburetor is constituted such that said second passage opening and closing device 16, when it controls a valve 19 to be lifted against a spring 17 at starting time, introduces an intake negative pressure to the negative pressure chamber 14 to close the opening and closing device 10 and enables an increased amount of fuel to be jetted from a bypass 3 and the idle port 4.
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