Let's talk about automobile engine. We all known very well there are two types of engine. We generally see petrol engine and diesel engine vehicle. Petrol and diesel engine further classification two stroke and four stroke engine.

Our bikes are generally  four stroke engine. So today let's talk about four stroke petrol engine.

There are one Power stroke in four time movement of piston in the engine cylinder so it is called four stroke engine. In simple words piston moves up and down in cylinder that is recriprocating motion and after four times motion there one time fuel burn and produce power to run the engine. 

Now talk about engine parts -

1 Cylinder 

2 piston

3 Inlet valve

4 exhaust valve

5 spark plug

6 crank case 

7 crank shaft 

8 connecting Rod 

9 crank pin 

Piston motion top to bottom is called stroke and same piston move bottom to top it also known stroke. 

Let's talk about working of petrol engine - There are four process done for combustion of petrol with oxygen. Every process there are called on stroke.

First stroke -  Piston moves top to bottom in cylinder engine and  inlet valve open exhaust valve closed. Air and petrol mixture enter in cylinder through Inlet valve from carburator.

Stroke 2 -  Both valve of Engine are closed and piston move bottom to top. Petrol and air mixture compressed. And due to compression heat gain. When piston just near the top spark plug generate spark. 

Stroke 3 - Mixture of petrol and air  Due to spark fuel is ignite and suddenly high pressure wave created which pushed piston bottom in the cylinder and both value closed.

Stroke 4- Now piston move upward and exhaust valve open and inlet valve closed. Burn gases out from exhaust valve. Inlet valve closed.

That process repeat. And engine working properly.

Four stroke engine vehicle example like a hero slender bike. It is  four stroke petrol engine. 

 In present time blended petrol are used. Indian government are ready to blended ethanol 10 percent in petrol by 2022. It means 10% ethanol mixed with 90% petrol. Indian government next target to 20% blended of ethanol in petrol engine. Blended petrol are helpful to reduce the fuel consumption

present time India oil corporation launched 100 octane value petrol. That petrol are used in bike which has high power. Petrol engine quality measure with the help of  it's octane number. 100 octane number means high quality and 0 means low grade fuel. Generally high grade fuel are good and large amount heat energy produced. That heat energy is primary sources of energy of vehicles. Due to engine work on heat energy so it called heat engine. 

Bajaj Pulsar type bike used two spark plug for better combustion of fuel and produce high amount of energy due to this acceleration of bike increase.