Valve system for an engine

A valve system for an engine comprising:

• an intake valve and an exhaust valve, said intake and exhaust valve having a valve body capable of closing one of an intake and an exhaust port, the intake and exhaust ports being provided in a cylinder head and opening to a combustion chamber;
• valve stems, one stem being connected to each valve body;
• a valve lifter supported in and axially slidable within said cylinder head;
• and
• a valve resting mechanism disposed between the valve stem associated with the valve and the valve lifter;
• wherein
• the valve resting mechanism enables an acting state and a non-acting state of a pressing force applied from the valve lifter to the valve in the valve opening direction,
• the valve resting mechanism including:
• a pin holder slidably fitted in said valve lifter, the pin holder having an essentially cylindrical shape with an end abutting the valve lifter opposite to a point wherein the valve lifter abuts a valve system cam, and an axis of the pin holder substantially parallel to an axis of the valve lifter, wherein a sliding hole is formed in the pin holder and has an axis substantially perpendicular to the axis of the pin holder, and an insertion hole opens into an inner surface of the sliding hole so as to allow the valve stem associated with the exhaust valve to be slidably inserted therethrough;
• a slide pin slidably disposed in the valve lifter and having one end facing to a hydraulic chamber, the slide pin having a containing hole coaxially connected to said insertion hole;
• a return spring for biasing the slide pin in the direction of reducing the volume of the hydraulic chamber;
• and
• a rotation stopping member passing diametrically through said slide pin for stopping rotation of said slid pin about its axis,
• wherein the rotation stopping member being mounted in a bridging portion of the pin holder, and the bridging portion is located at a top and bottom side of the pin holder.