Controls air intake and exhaust gas out from cylinder in correct time periods.
Intake valve and exhaust valve.
valves are use in four stroke engine, and ports are use in two stroke engine.
Jason
In a four-stroke reciprocating engine, both valves—the intake valve and the exhaust valve—open to facilitate the engine's four distinct strokes: intake, compression, power, and exhaust. The intake valve opens to allow the air-fuel mixture into the combustion chamber during the intake stroke, while the exhaust valve opens to release exhaust gases after combustion during the exhaust stroke. This coordinated opening and closing of the valves ensure efficient engine operation and optimal performance.
Tappet
Tappet
In a four-stroke engine, the intake valve opens in the intake stroke, allowing air-fuel mixture to enter, while the exhaust valve remains closed. During the compression stroke, both valves stay closed to build pressure. In the power stroke, the fuel ignites, pushing the piston down, with both valves still closed to retain pressure. Finally, in the exhaust stroke, the exhaust valve opens, allowing gases to escape, while the intake valve stays shut. This cycle repeats continuously, ensuring efficient engine operation.
Explain the advantages of four-stroke engine over two-stroke engine
What is the Mercury 3.5 Hp four stroke valve clearance?
in my opinion a two stroke engine is a better quality engine as compared to a four stroke engine!
two stroke
On an overhead cam engine, the lobes on the cam push the rocker arms which push the valves open.