US Patent 7293536 Two-cycle combustion engine

To provide a two cycle combustion engine provided with scavenging passages of a structure, which is effective to minimize a deposit of fuel contained in an air/fuel mixture and allows the mixture to be injected into a combustion chamber so as to avoid the blow-off of the air/fuel mixture, the engine includes a cylinder block 1 having a cylinder bore 1a, a scavenging-passage-defining wall member 34 made separate from the cylinder block 1 and fitted to the cylinder block 1. A scavenge regulating segment 37, 38 secured to the scavenging-passage-defining wall member 34 is spaced from an outer diametric surface 24C, 27C of the scavenging passage 24, 27 and two side surfaces 24A, 24B or 27A, 27B of the scavenging passage 24, 27 that are opposed to each other in a direction circumferentially of the cylinder bore 1a and occupies a circumferential center portion of the scavenging passage 24, 27.