| 摘要 |
PURPOSE:To aim at the ideal setup of a spark plug, by forming a head cover into almost U-shaped form in a plane view, forming a slit almost orthogonal with an overhead camshaft, and setting up the spark plug in this slit, while setting up a bolt, clamping the head cover, in the specified position. CONSTITUTION:In an interspace between joined surfaces of a cylinder head 32 and a head cover 34, a camshaft 36 is pivotally supported in lateral. On the other hand, each cooling air passage 82 is formed in the cylinder head 32 and the head cover 34. In addition, in this cooling air passage 82, a part to be approached to a bearing 80 of the camshaft 36 is formed into a cylindrical space between exhaust values 64, setting this space to a spark plug detachable hole 84. And, a spark plug 86 is set up so as to make it come nearer to the bearing 80 with the spark plug detachable hole 84, and an ignition part of the spark plug 86 is set up in and around the center of a combustion chamber. And, among plural pieces of bolts 96-102 clamping the head cover 34 to the cylinder head 32, two bolts 100 in the inner part of the spark plug detachable hole 84 are set up so as to hold the spark plug 86 in between, thus sealability is improved.
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