| 摘要 |
PURPOSE:To keep a valve switching timing constant, by fitting a valve driving means to a spherical intake/exhaust valve integrally, and allowing the valve driving means to be rotatably pivoted in the pivot section of an engine body. CONSTITUTION:A pivoting protrusion 14b is provided at the face-to-face end of a spherical intake/exhaust valve 14 so as to be held between a cylinder head 4 and a head cover 5. A base shaft 19 is installed so as to protrude on the other end of the valve 14, and a valve driving shaft tube 21 is integrally fitted to the base shaft 19. The inside periphery 24a of a spherical bearing 24 is fitted integrally to the expanded section 21a of the valve driving shaft tube and its outside periphery 24b is loosely fitted to a driven gear support shaft 25. The aforesaid constitution enables the valve to transmit a switching torque without looseness in the valve, and thereby allows a valve switch timing to be kept constant.
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