| 摘要 |
PROBLEM TO BE SOLVED: To omit the use of a spring with a high tension by forming part of a portion being fitted of a camshaft on a flat stopper surface, forming the inner surface of a decompressor cam into the L-shape to form a first and a second flat surfaces, and latching the first flat surface of the decompressor cam with the stopper surface when the decompressor is turned ON. SOLUTION: When the decompressor is turned ON, the tension of a spring 13 pulls an arm 9 inward, causing a decompressor cam 10 to protrude upward from a base circle 16 of a cam 4. This protrusion causes the arc surface of the decompressor cam 10 to contact the bottom surface of a tappet, releasing a valve by a small margin. At this time, a first flat portion 14 on the inner surface of the decompressor cam 10 coexists on a stopper surface 5 of a camshaft 1. Even if a valve spring tension acts as the valve rides over the tappet, the arm 9 will never swing outward until the point of contact between the tappet and decompressor cam 10 exceeds a line A-B. When the line A-B is exceeded, the arm 9 is pushed out by the valve spring tension, thus preventing wedging in the stopper surface 5.
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