The pistons of the pressure flammable fuel and pass it through the connecting rods to the crankshaft of the engine. In these types of engines are used special pistons having a star-combustion chamber. The main components are the bottom of the piston of the piston ring zone with piston rings, skirt and piston pin boss. Piston fingers are fixed retaining rings in piston lugs. The two upper piston rings (o-rings) prevent breakthrough of the gases from the combustion of fuel in the crankcase. The lower (oil ring) removes excess oil from the cylinder wall and throws them into the crankcase.