The Spark Ignition Engines is a petrol engine often used on commercial vehicles such as scooters, motorcycles, cars, etc. It produces less noise and vibration, is easier to start, requires less maintenance, and has lighter weight. In their definition, we can say that S.I. engines are internal combustion engines that operate on the principle of spark ignition (which is to create a spark with a spark plug).
It uses petrol and fresh air to complete the Otto cycle. The four-stroke petrol engine performs the work cycle in four stages. During that time, the crankshaft takes two turns. The first cycle is intake - the clip goes from TDC (top dead center) to BDC (bottom dead center), the suctions valve starts to open before the piston reaches TDC and closes after the piston passes the BDC position.
A pressure of 0.7–0.9 bar is produced in the cylinder, which, through an open valve, draws a freshly worked mixture that is mixed into the cylinder with the remaining combustion products from the previous process. During compressions, the clip moves to TDC and compresses the gases in the cylinder. Pressure increases from 11 to 18 bar and temperature from 400 to 600 0C. The piston-cylinder starts to reduce chamber space.