A simulation model for crankcase scavenged 2-stroke cycle SI engine has been developed to predict the performance and scavenging characteristics. A suitable coupling of scavenging and combustion processes has been achieved to enable these predictions.Scavenging process has been analysed through a 3-phase, that is, displacement, short circuiting and mixing, model capable of taking any combination of these phases. The flow of fresh charge in the exhaust during mixing period is modeled based on ‘S’ shape concept. The back flow through the ports is also considered.The combustion analysis uses quasi-dimensional eddy entrainment concept that includes the basic turbulent parameters.The results concerning the combination of displacement, short circuiting and mixing phases are analysed to judge the scavenging characteristics of the enginefrom its overall parameters. The predictions of cylinder pressure time history at different speeds, equivalence ratios and compression ratios are made. A comparison with experimental results is also made. The predicted and experimental results show good agreement.