A multidimensional calculation method is used to investigate the flow in a motored two‐stroke engine. The governing equations are written in a moving‐coordinate system such that the grid can move with the piston. Grid lines are added into or deleted from the computational domain, depending on opening or closure of the ports. The EPISO algorithm is modified and adopted as the solution procedure. Calculations are performed on an engine of loop‐scavenged type. Details of the gas exchange process and the flow structure in the cylinder are shown. The effects of the engine speed, inlet discharge coefficient and the angle of boost port are examined.