Exhaust control apparatus for a spark-ignition two-stroke internal combustion engine

摘要

An exhaust control apparatus for a high level engine output and engine efficiency for obtaining a stable operation from a low speed to a high operating speed in a spark-ignition two-stroke internal combustion engine with an exhaust timing that can be adjusted. A spark-ignition two-stroke internal combustion engine is equipped with an exhaust channel that opens via an exhaust port into the cylinder, and an exhaust control valve that is supported for reciprocation along the cylinder centerline direction along the exhaust port and that allows at least the portion of the exhaust port on the cylinder head side to be blocked. A valve body depression forms a hollow from the cylinder head side to the crank side in the exhaust control valve by a bottom wall, side walls, and a control wall. A housing depression is provided that allows the above-mentioned exhaust control valve to be withdrawn from the abovementioned exhaust channel. A communicating hole allows a space, which is bounded by the housing depression and the valve body depression, to communicate with the above-mentioned exhaust channel which is provided on the bottom wall of the exhaust control valve.