| 摘要 |
PURPOSE:To operate a valve to be smoothly opened and closed, by forming the surface of a valve stem to a stopped shape and scraping off oil mist varnish and sludge adhering to a valve guide surface. CONSTITUTION:Intake and exhaust valves 14 are arranged to the side part of a cylinder 10, and a spring chamber 17 provided to the bottom part of the intake and exhaust valves 14 is communicated to a crank chamber. Blow-bye gas containing oil mist from the crank chamber is introduced to an intake system via the spring chamber 17. A surface of a valve stem 15 protruded to the spring chamber 17 from a valve guide 16 is formed to a stepped shape 15a in an area slidably shuttling internally and externally of the valve guide 16. Varnish and/ or sludge of high viscosity in an internal surface of the valve guide are scraped off by a stepped part, and opening and closing operation of the valve is never disturbed, then smooth operation of the valve is obtained. |
