Patent ID: 8181611

Claim:
A stratified scavenging two-cycle engine comprising: a cylinder; a piston; a crank chamber; a scavenging channel including a crank-chamber side portion that extends along the crank chamber and a cylinder-side portion that extends along the cylinder; an external air introduction path for introducing lead air into the scavenging channel, the external air introduction path being connected to an intermediate position of the scavenging channel; and an opening portion formed in the piston; wherein: the opening portion and a scavenging port are relatively positioned such that when the piston is located close to top dead center, the scavenging port is opened via the opening portion so that the crank chamber communicates with the scavenging channel via the opening portion and the scavenging port; and the engine comprises communication-preventing means for preventing communication between the crank chamber and the crank-chamber-side portion of the scavenging channel through a starting point of the scavenging channel that is open to the crank chamber, when the piston is located close to top dead center, such that an air-fuel mixture remaining in the cylinder-side-portion of the scavenging channel is pushed out by the lead air introduced via the external air introduction path and caused to flow into the crank chamber via the scavenging port when the piston is located close to top dead center.