Abstract: The mold comprises an outer mold part (10) which defines a mold cavity (11). Walls of the outer mold part form the outer surface of the combined engine block and cylinder head. There also are first and second inner mold parts (12, 13) which extend into the mold cavity and are maintained a distance from each other. Each of the first and second inner mold parts have a cylindrical portion (12a, 13a) which, during the casting procedure, forms the cylinder bores in the engine block. The first and second inner mold parts (12, 13) also each have an upper portion (12b, 13b) situated above the cylindrical portion. During the casting procedure the upper portions form portions of a combustion chamber common to the cylinder bores. The mold further includes an third inner mold part (15) which extends through the outer mold part (10) and cooperates with the first and second inner mold parts (12, 13) to form the combustion chamber during the casting procedure.

Abstract: The invention relates to a more complex but considerably more emission-poor two-stroke engine than the conventional one. The HC-emissions become zero when completely burned. CO is controlled by the mixture ratio and NO.sub.x becomes very low owing to the built-in EGR.A super charger (20) presses air through the cylinder after the power stroke and dilutes the exhaust gases. A carburettor unit (21) is fed by the super charger and presses an overrich gas mixture into the cylinder at the beginning of the compression stroke. A slide gate (22) controls the connection between the carburettor unit and the cylinder.