Internal combustion engines are the machines in which fuel burns immediatly within operating space,and the heat energy which is arised there converses into memehanical work. Engine is a machine which converts some kind of energy into a mechanical work. Working cycle of two-stroke engine takes place in one cranckshaft i.e. in two working strokes. Four-stroke working cycle takes place only in a cylinder in four tacts. (two crankshaft turn). The function of the fuel supply system equipe engine miksture system with sufficent amount of fuel in all engine operating regimes. Through this work we are going to be introduced with otto motor's parts and their working methods.