| 摘要 |
PURPOSE:To form the cylinder wall of an engine into a relatively small thickness and simplify its construction, at a part where a valve for changing the exhaust timing is provided. CONSTITUTION:A recess 11 is formed corresponding to the top edge part of an exhaust port 10 in a cylinder 1, a valve 13 is provided therein. In accordance with a rotational speed of the engine an operating shaft 19 is rotated, and the valve 13 is shifted along an axial direction of the cylinder 1 through an operating arm 22, link member 24 and sliding rod 14 to change a height of the opening port of the exhaust hole 10 thus to change the exhaust timing. Said valve 13 being shifted along the axial direction of the cylinder 1, its width in a diametric direction of the cylinder 1 is only required to have a dimension enough for obtaining the necessary strength, thus the wall of the cylinder 1 can be made relatively thin in its thickness, and its construction can be simplified. |
