What is carburetion

Introduction :

Spark-ignition engines normally use volatile liquid fuels. In SI engine the preparation of fuel-air mixture is done outside the engine cylinder and make a homogeneous mixture that is not completed in the inlet manifold. Fuel droplets which remain in suspension continue to evaporate and mix with air even during suction and compression stroke. The process of mixture preparation is extremely important for spark-ignition engines. 

Definition of carburetion :

The amount of formation of a combustible air-fuel mixture by mixing the proper amount of fuel with air before admission to engine cylinder is called carburetion.

The device which does this job is called carburettor.

The carburettor should provide an A/F ratio in accordance with engine operating requirements and this ratio must be within the combustible range.