Abstract: In order to facilitate start-up of an internal combustion engine, a valve device mounted on a cylinder of the internal combustion engine and enabling a combustion chamber in the cylinder to communicate with the atmospheric air comprises a casing having a first path, an accumulator and a second path, the first path communicating the accumulator to the atmospheric air, the second path communicating the accumulator to the combustion chamber when the valve device is mounted on the cylinder; a valve disposed in the accumulator and associated with the first path; a check valve mechanism disposed between the accumulator and the second path; and a spring biasing the valve in such a direction that the valve does not close between the accumulator and the first path. Further, the valve device comprises a third path communicating the accumulator to the outside thereof.

Abstract: To facilitate start of a 2-cycle engine, for instance, compression pressure at the first compression stroke is released through the valve to reduce reaction force applied to an engine starter; once the mixture is ignited, explosion pressure at the first explosion stroke and after is accumulated in the accumulator space through the check valve member to keep the valve member closed against the valve spring, so that the engine is operated under the ordinary conditions; when the engine is at halt, accumulator pressure is released through the openable check valve member and the valve member opened by the valve spring to its original conditions.