| 摘要 |
PURPOSE:To prevent an engine from becoming large in size as well as to enhance freedom in layout by containing a cam chain tensioner adjusting device, the retreatment prevention mechanism of which is adapted to be controlled in disengagement from outside, in a cylinder block. CONSTITUTION:An adjusting device 22 is contained in a cylinder block 1, thereby pushing a chain tensioner 14 so as to unable a pressure piece 26 to retreat for maintaining stable operations thereof while certain tension is constantly held following the stretch of a cam chain 11. Therefore, timing for the opening and closing of a suction/exhaust cam is accurately maintained. When the cam chain 11 has to be removed for maintenance and the like, a screw plug 35 is removed, a screw driver is inserted into a driver insertion hole 34, then a screw member is turned, thereby enabling the chain tensioner 14 to retreat in a simple manner. Therefore, the adjusting device 22 can be contained in the minimum space required of a cylinder block 1, thereby preventing the cylinder block 1 from becoming large in size.
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