The 2 stroke engines have wide variety of applications, especially in the field of recreational vehicles, handled products and small two wheelers. This is due to the 3 advantages that characterize these kind of engines: the high power density, the low weight and the low production costs. The main research activities in this field are focused on the optimization of these advantages while minimizing the well known disadvantages: high emissions and fuel consumption. The aim of this work is the development of a simulation methodology able to predict the performance of the engine under development with special attention to the scavenging process, mixture preparation and combustion.