| 摘要 |
PURPOSE:To prevent any prefiring from occurring in a low-speed range as well as to secure high engine power in a high-speed range, by making the rocking displacement of a valve seat plate so as to set it to a close position in the low- speed range but to an open position in the high-speed range, respectively. CONSTITUTION:In an engine low-speed range, a valve seat plate 9 is set to a close position as shown in a dotted line. An air-fuel mixture enters a crankcase 4 from a first passage 1a where a reed valve 8 operated along with a second passage 1b. The reed valve 8 comes somewhat to suction resistance but prefiring is in no case produced there. In an engine high-speed range, the valve seat plate 9 is set to an open position as shown in a full line. The air-fuel mixture enters the crankcase from the second passage 1b and the first passage 1a which is opened because of the reed valve 8 being retreated together with the valve seat plate 9, thus a high engine power is obtained. |
