Schnuerle scavenging two-stroke engine

A Schnuerle scavenging two-stroke engine including a plurality of scavenging passages each having a scavenging port that is an opening opened and closed by a piston, with scavenging gas discharged from the plurality of scavenging ports being directed toward an intake-side cylinder wall surface opposite to an exhaust port in a scavenging process, the scavenging gas impinging on the intake-side cylinder wall surface and reversing to head for the exhaust port, wherein

• the scavenging passage related to at least one of the plurality of scavenging ports has, at its upper end portion, an intake-side wall surface that, at a height level of the scavenging port, defines a first flow direction of scavenging gas discharged from the at least one scavenging port into a combustion chamber, the engine comprising:
• a guide portion disposed at the upper end portion of the scavenging passage related to the at least one scavenging port, for defining a second flow direction of scavenging gas discharged from the at least one scavenging port into the combustion chamber, wherein
• the second flow direction is inside a cylinder relative to the first flow direction,
• the guide portion has a guide surface disposed at the upper end portion of the scavenging passage related to the at least one scavenging port, for directing a flow direction of scavenging gas rising through the scavenging passage toward an inner side of the cylinder in the scavenging process, and
• when the at least one scavenging port begins to open with descent of the piston and accordingly as the opening increases, the direction of flow discharged from the at least one scavenging port changes from the first flow direction to the second flow direction.