Method of operating a two-stroke-cycle engine with variable valve timing in a four-stroke-cycle mode

Method of operating an internal combustion engine of the type comprising a piston reciprocable in a cylinder, intake port means for admitting air into the cylinder, an exhaust valve that is opened and closed by valve actuator means independent of crankshaft position, spark ignition means, and fuel injection means, said method comprising the following steps during a four stroke cycle

• during a first stroke wherein the piston moves from BDC to TDC, admitting air to the cylinder via said intake port means, closing the intake port means by movement of said piston, closing the exhaust valve, and injecting the fuel into the cylinder,
• during a second stroke wherein the piston moves from TDC to BDC, maintaining the exhaust valve in the closed position, thereby lowering the pressure of the fuel air mixture,
• during a third stroke wherein the piston moves from BDC to TDC, increasing the pressure of the fuel air mixture followed by spark-igniting the mixture,
• during a fourth stroke wherein the piston moves from TDC to BDC, expanding the ignited fuel air mixture followed by opening said exhaust valve and said intake port, thereby purging the cylinder of exhaust gas.