In order to assist engine design through a better understanding of the direct-fuel-injection of two-stroke gasoline engines, a simulation model has been established using a multidimensional CFD code. Two-phase flow in the changing geometry of the engine was evaluated. To obtain a developed fluid flow field for the fuel-injection cases, two full engine cycles were computed. Two cases were analyzed, one with the injector at the cylinder head and the other at the cylinder side wall. The gas flow field, fuel droplet distribution and fuel vapor concentration were obtained and compared for the two cases.