AIR LEADING-TYPE STRATIFIED SCAVENGING TWO-STROKE INTERNAL-COMBUSTION ENGINE

The certainty of supplying air to a scavenging channel through a piston groove is improved. In a cylinder wall 2 , a gas venting port 10 is formed below and adjacent to a scavenging port 6a . The gas venting port 10 is independent from the scavenging port 6a , and is opened/closed by a piston as each of an air port 4a and the scavenging port 6a is. Upon a piston groove 8 being brought into communication with the gas venting port 10 as a result of the piston moving up (FIG. 1 ( II )), blown-back gas in a piston groove 8 can move to a crankcase through the gas venting port 10 . Along with this, air can enter the piston groove 8 from the air port 4a .