A two-dimensional model has been developed to study the flow field, turbulence levels, combustion and heat transfer losses in a two-stroke, gasoline-injected, engine. The model accounts for the mean axial, radial and azimuthal (swirl) velocity components and for the engine turbulence by means of a two-equation model of turbulence. A one-step overall chemical reaction has been employed to study the fuel consumption and flame propagation in a geometrical arrangement where the intake port is circumferentially located at the cylinder wall and covered/uncovered by the piston, and the exhaust valve is simulated as an infinitesimally thin disk located at the cylinder head which penetrates into the engine cylinder. The fuel injector is located at the cylinder head. Numerical calculations indicate that the mean velocity field in the engine cylinder is controlled by the large scale vortical structures created in the intake stroke. These structures are damped away in the compression stroke.