| 摘要 |
PURPOSE:To arrange an ignition plug at the central section of a cylinder, and to simplify a valve mechanism by disposing a cam shaft and a rocker shaft on the cylinder axis of a cylinder head cover one by one and up and down and driving a pair of intake and exhaust valves. CONSTITUTION:A pair of intake and exhaust valves 10, 11 are arranged so as to surround a cylinder axis A, and a cam shaft 24 and a rocker shaft 26 are installed vertically to a heat cover 17 in parallel with the direction of arrangement of valves of the same kind as the intake and exhaust valves 10, 11. Two rocker arms 30 driving the intake valve 10 are mounted to the rocker shaft 26 so as to hold a rocker arm 31 driving the exhaust valve 11, and a space in which an ignition plug 16 is fitted is formed between the two rocker arms 30 for the intake valve. The ignition plug 16 can be disposed on the cylinder axis A, only the cam shaft and the rocker shaft may be used severally, a valve mechanism can be simplified, the mechanism can be assembled previously to the head cover and assembly is facilitated. |
