Abstract: A two-cycle internal combustion engine comprises a cylinder with a piston, the cylinder having a port in which an intake valve is placed for feeding a fuel-air mixture from an intake manifold into an intake chamber. The intake chamber is positioned under the position, is isolated from a crank chamber and communicates with a combustion chamber. The combustion chamber is positioned above the piston and communicates with the intake chamber by means of a by-pass manifold, at the inlet of which an intake valve is placed for feeding a fuel-air mixture. An additional piston is provided which is positioned in the cylinder between the crank chamber and the main piston and is rigidly connected to the main piston. A second intake chamber is positioned between the first intake chamber and the additional piston. The second intake chamber isolated from the first intake chamber by means of a partition and communicates with the intake manifold and with the by-pass manifold.