US Patent 7213544 Exhaust-outlet control for 2-stroke engine

An exhaust valve assembly for a two stroke internal combustion engine having a cylinder with at least one main exhaust port and one auxiliary exhaust port is disclosed. The assembly comprises a main exhaust valve for at least partially closing the main exhaust port, an auxiliary exhaust valve for at least partially closing the auxiliary exhaust port, the auxiliary exhaust valve being separate from the main exhaust valve, and an actuator for actuation of the main exhaust valve and the auxiliary exhaust valve, wherein the actuator is connected to the main exhaust valve and the auxiliary exhaust valve is connected to the actuator by the main exhaust valve.