| 摘要 |
PURPOSE:To make an engine size small with reduced distance between rocker arms by tilting an axis of a spark plug cover tube against an axis of a cilinder bore and at the same time forming thinned parts on bosses of respective rocker arms for suction and exhaust valves. CONSTITUTION:An axis 16 of two suction valves 12's and an axis 17 of two exhaust valves 13's are tilted against an axis 18 of a cylinder bore 2 by suitable angles of theta1 and theta2 in the opposite direction each other in a V type as a whole. A cam shaft 19 is pivoted between the two suction valves 12's and the two exhaust valves 13's with rocker arms 20 and 21 respectively for suction and exhaust valves arranged in parallel with the cam shaft 19. In the above constitution, an axis 30 of a cover tube 29 for attaching a spark plug 8 to a cylinder head 3 is tilted against the cylinder bore 2 axis 18 by a suitable angle theta3. Thickness T of a boss part 24a of one rocker arm, e.g., 24 is thinned to T1 at the location where one end part 23b of the other rocker arm 23 faces.
|
