Patent attributes
An engine valve operating system is provided in which a roller in rolling contact with a valve operating cam of a camshaft is axially supported via a roller shaft on a roller support portion provided on a first rocker arm, a second rocker arm having a cylindrical boss portion pivotably supported on a support shaft and an arm portion extending from the boss portion and having a sliding surface that is in sliding contact with the roller shaft is operatively connected to an engine valve, and the position of either one of first and second rocker arm swing axes is changed within a plane perpendicular to the axis of the camshaft, wherein at least the roller support portion (38) of the first rocker arm (23) is disposed at a position that overlaps the second rocker arm (26A, 26B) in plan view. This can provide an engine valve operating system that enables the size thereof to be reduced in a direction along the axis of the camshaft.