| 摘要 |
PROBLEM TO BE SOLVED: To secure a predetermined fuel amount in a low speed operating region of an engine and improve characteristics of a fuel amount in a high speed operating region of the engine by increasing a length of a passage from a constant pressure fuel chamber to a fuel jet. SOLUTION: A pillar shaped rotary throttle valve 3 having a throttle hole 4 is rotatably and elevatably supported on a cylindrical valve chest 2 crossing an intake passage 4A of a carburetor body 30. A fuel supply pipe 5 supported on a bottom part of the valve chest 2 is projected to the restriction 4, and a needle 33 supported on the throttle valve 3 is fitted into the fuel supply pipe 5. A constant pressure fuel chamber 13 is arranged on a lower surface of a middle wall body 38 joined with a lower surface of the carburetor body 30, and first and second chambers 8, 6 are separately arranged on an upper surface of the middle wall body 38. A check valve 53 and a fuel jet 7 are arranged on a passage for connecting the first chamber 8 and the fuel supply pipe 5. The constant pressure fuel chamber 13 is connected with the second chamber 6 through a passage 10, and the second chamber 6 is connected with the first chamber 8 through a passage 9.
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