| 摘要 |
PURPOSE: To facilitate works of maintenance and the like for bolts, inlet valves and exhaust valves, even when an engine is made compact. CONSTITUTION: More than two inlet apertures 18, 19 are provided right and left for side-by-side in one side in the back and forth directions of a cylinder 7. A plurality of exhaust apertures 24 the number of which is smaller than that of inlet apertures 18, 19 are provided right and left for side-by-side in the other side. Inlet valves 26, 27 which open and close each inlet aperture 18, 19, respectively, are provided, and also exhaust valves 32 are provided which open and close each exhaust aperture 24 respectively. When viewed from the side, an intersecting angle made by the axis of a cylinder 2 and the axis 73 of the inlet valve 26 at the center region is expressed as the first intersecting angleθ1. An intersecting angle made by the axis 3 of said cylinder 2 and the axis 74 of the inlet valve 27 in the side part is expressed as the second intersecting angleθ2. An intersecting angle made by the axis 3 of the cylinder 2 and the axis 75 of a exhaust valve 32 is expressed as the third intersecting angleθ3. And the three intersecting angles are formed so as to be the first intersecting angleθ1<the second intersecting angleθ2<the third intersecting angleθ3.
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