Air-Fuel Mixture is the combination of the air and fuel (the fuel will be petrol in maximum cases) in a specific ratio that will help the engine to work properly. Every petrol engine will suck the air-fuel mixture for its suction process and the mixture will burn (or combust) using the sparks which result in the combustion process.

Types Of Air-Fuel Mixtures:

Engines will not work under the same conditions throughout the process. Sometimes, the engine will be run at slow conditions, sometimes at high and medium so, the speed of the engine will depend upon the air and fuel mixture input. So, the types of air-fuel mixture depend upon the types of speeds that the engine will be run.

The types of engine speeds will be classified as low, normal, and high speeds; according to it, the types of air-fuel mixtures will be

• Lean Mixture
• Stoichiometric Mixture and
• Rich Mixture

Stoichiometric Mixture:

The Stoichiometric Mixture is one of the types of air-fuel mixture that has a mixture figure of 15:1. It does mean that the engine consumes 15 parts of Air and 1 part of Fuel (petrol) for its starting. The stoichiometry mixture is the mixture that requires a normal speed of bike or motorcycle.

We can even prescribe the explain that if an engine requires to run at the economy stage then the throttle valve will allow the air-fuel mixture of around 15:1.

Lean Mixture:

The Lean mixture is another type of air-fuel mixture that the engine will consume less air-fuel ratio and runs at low speed. The air-fuel mixture will be around 12:1 which means the 12 parts of air are mixed with 1 part of fuel (petrol).

If we compare the lean mixture with the stoichiometric mixture then we can that the stoichiometric mixture consumes more fuel.

Rich Mixture:

Now, talking about the rich mixture (one of the types of air-fuel mixture), as the name indicates, the engine will consume more fuel and air for its working. The air-fuel mixture will be appropriately around 17:1.

If we observe carefully, the rich mixture will be used at high speeds. As the speed is high, the consumption of the air and fuel mixture is also high. If we observe carefully, the fuel consumption in the rich mixture will be high compared to the stoichiometric mixture and lean mixture.

For example: If the car or bike is required to climb the high elevations on the roads then the normal speed will not be required to overcome the height instead, the car or bike will go back.

So, to overcome the high elevations it is necessary to increase the engine speed which may require accelerating more and consumption of fuel increases.

We can say that the mixture ratio will be increased as the acceleration increasing and the increased ratio is called as the Rich Mixture.