| 摘要 |
An engine includes an engine body and pistons reciprocally disposed within the engine body. The engine body and the piston together define a combustion chamber. The engine body defines an intake passage communicating with the combustion chamber at an intake port thereof and an exhaust passage communicating with the combustion chamber at an exhaust port thereof. At least one intake valve is arranged to move between an open position and a closed position relative to the intake port. At least one exhaust valve is arranged to move between an open position and a closed position relative to the exhaust port. A camshaft shaft is journaled for rotation within the engine body. A rocker arm shaft also is disposed within the engine body. Intake and exhaust rocker arms are pivotally mounted on the rocker arm shaft. The intake rocker arm is associated with the intake valve. The exhaust rocker arm is associated with the exhaust valve. The camshaft actuates the intake and exhaust valves through the intake and exhaust rocker arms, respectively. The rocker arms are axially moveable along an axis of the rocker arm shaft. A stopper is disposed on the rocker arm shaft to stop the axial movement of the rocker arms in one direction. A spring member is mounted on the rocker arm shaft opposite to the stopper to urge the rocker arms toward the stopper. A block member is arranged to block the axial movement of the rocker arms toward the biasing member.
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