This paper reports the investigation on the scavenging process in a model cylinder having a cross-scavenging system. The movement of the scavenging front in the cylinder ana the shortcircuiting of fresh charge were recorded by an electronic method(1). Hence the profile of the scavenging front was made clear. The port arrangement investisated gives a "flat scavenge", pattern and an early short-circuiting occurs at the exhaust ports located near the scavenging ports and the fresh charge leaves the upper part in the exhaust side unscavenged.