Loop scavenged two-stroke internal combustion engine

A loop scavenged two-stroke engine comprising:

• one or more pairs of opposing first and second scavenging passages which adopt a reverse scavenging system to cause a combustion operation chamber formed above a piston and a crank-chamber to communicate with each other via the scavenging passages and to cause a scavenging gas in the crank-chamber to be sucked into the combustion operating chamber through the scavenging passages,
• wherein only a first guide wall surface located on an intake port side of the first scavenging passage and a second guide wall surface located on the intake port side of the second scavenging passage are disposed such that a first horizontal scavenging angle defined between a center line of an opening of an exhaust port and a first extension line extending from the first guide wall surface to the center line differs from a second horizontal scavenging angle defined between the center line of the opening of the exhaust port and a second extension line extending from the second guide wall surface to the center line, such that a main flow of a scavenging flow blown out from the first scavenging passage and a main flow of a scavenging flow blown out from the second scavenging passage intersect each other or collide with each other in plane view at a position shifted in a lateral direction from the center line of the opening of the exhaust port.