| 摘要 |
PURPOSE:To improve engine performance in time of low speed without detracting from the performance in time of high speed, by installing a separate wall, whose one end separates from the top of a suction passage inner wall, inside a suction passage. CONSTITUTION:Partitioning a suction passage 13 into two parts, a separate wall 14 extending toward a carburetor 12 is installed, and its supper end 14a is made to separate from an inner wall surface 13a of the suction passage. With this constitution, at a high speed range, an air-fuel mixture passes through a throttle valve 23 being opened in almost parallel with an air passage 22 and flows into the inside of a combustion chamber A along the inner wall surface 13a of the suction passage 13 by dint of centrifugal force. At a low speed range, the throttle valve 23 opens or closes so as to make its more downstream side than a rotation center come close to the down wall side of the air passage 22 and its upstream side approximate to the upper wall side, so that the air-fuel mixture flows into the inside of the combustion chamber A along an inner wall undersurface 13b of the suction passage 13. |
