There's no more doubt about it, 4 stroke ATV exhaust system is highly popular and is preferred by many ATV users. This concept is more fuel efficient and clean burning compared to two stroke cycle engine. Four stroke cycle requires more moving parts and manufacturing expertise. 4 stroke ATV exhaust system is definitely easily manufactured in multi-cylinder configurations, thus making it useful in high-output applications. So how does four cycle engine work? A basic thing you must know is the fact that it is characterized by straight movements alternately, back and forth of a piston inside a cylinder. They are the intake induction stroke, compression stroke, power combustion stroke, and exhaust stroke. This 4 stroke cycle begins at the top dead center while the piston is at its peak point. On the first intake of the piston, a mixture of fuel and air is drawn into the cylinder through the intake port. Now, the intake valve closes and the subsequent upward stroke or compression compresses the fuel- air mixture. This mixture is subsequently ignited basically by the heat and pressure of compression at roughly the top of the compression stroke. The piston is then forced to downward for the third stroke by the resulting expansion of burning gases. Finally, the fourth and last upward stroke evacuates the spent exhaust gases from the cylinder past then open exhaust valve through the exhaust port. Four stroke engine basically depends on the piston's motion to draw in fuel and air and to move out the exhaust gasses. The increasing volume within the cylinder causes a partial vacuum which draws in the air and fuel mixture as the piston descends. As the piston reaches bottom dead center, after ignition of the fuel and air charge, the combustion lowers down. Engine's power output depends on the ability of the engine to allow large volume flow of both air-fuel mixture and exhaust gas through the particular valve sports usually located in the cylinder head. The power amount generated by a 4 stroke engine is in due course limited by piston speed due to material strength.