Patent ID: 7025021

Claim:
A crankcase scavenged two-stroke internal combustion engine comprising: a piston reciprocatingly arranged within a cylinder; a flow path configured to selectively place an air inlet duct in fluid communication with a scavenging duct; said air inlet duct being equipped with a restriction valve controlled by an engine parameter for controlling an amount of air permitted to pass through said air inlet duct; said air inlet duct extending to an air inlet port formed in a cylinder wall of said engine and said scavenging duct extending from a scavenging port formed in said cylinder wall of said engine; said air inlet port being positioned in said cylinder wall so that when said piston is positioned in a top dead center configuration, said air inlet duct is connected in fluid communication with said flow path; said flow path being configured to extend from said air inlet duct to said scavenging duct when said piston is in said top dead center configuration so that a period of air supply through said air inlet duct to said engine is approximately as long as a period of fuel and air mixture supply to said engine during substantially each cycle of said two-stroke internal combustion engine; and an upper edge of said air inlet port is located at least as high in said cylinder's longitudinal axial direction as a lower edge of said scavenging port.