Internal combustion engines

Claim 1

IN A FOUR-CYCLE INTERNAL COMBUSTION ENGINE, A CYLINDER INCLUDING A HEAD FORMING A COMBUSTION CHAMBER, A PISTON RECIPROCABLE IN SAID CYLINDER, INTAKE AND EXHAUST PASSAGES TO AND FROM SAID COMBUSTION CHAMBER, INTAKE AND EXHAUST VALVES FOR OPENING AND CLOSING SAID PASSAGES, A CARBURETOR HAVING A THROAT LEADING TO SAID INTAKE PASSAGE, A BUTTERFLY THROTTLE VALVE IN SAID CARBURETOR THROAT AND CONTROL MEANS THEREFOR, A SCAVENGING PORT IN THE WALL OF SAID CYLINDER LOCATED TO COMMUNICATE WITH SAID COMBUSTION CHAMBER ONLY WHEN SAID PISTON APPROACHES ITS BOTTOM DEAD CENTER POSITION, SCAVENGING VALVE MEANS OPENING AND CLOSING SAID SCAVENGING PORT FOR ADMITTING A FLOW OF SCAVENGING AIR TO SAID COMBUSTION CHAMBER, AND A LINKAGE BETWEEN THE SAID THROTTLE VALVE CONTROL MEANS AND SAID SCAVENGING VALVE WHEREBY WHEN SAID THROTTLE VALVE IS AT ITS IDLE OR NEAR IDLE POSITION THE SCAVENGING VALVE MEANS IS OPEN, AND MEANS OPERABLE RESPONSIVE TO THE PRESSURES IN SAID INTAKE PASSAGE MODIFYING THE ACTION OF THE LINKAGE BETWEEN THE SAID THROTTLE VALVE CONTROL MEANS AND SAID SCAVENGING VALVE.