shirindahetsudo structure null of engine for motorcycle

摘要

PURPOSE:To surely drain water from the upper section of a cylinder head, by forming a vent hole in the cylinder head, piecing through the front section of the cylinder head obliquely downward from the position of attachment of a spark plug by way of a section above an exhaust passage. CONSTITUTION:A spark plug 4 is provided in one side of a convex wall 8 formed on the upper section of a cylinder head 1, being longitudinally extended. Convex walls 6, 7 are formed in the front and back sides of the spark plug 4, being transversely extended. A drain hole 13 is formed in the cylinder head 1, piercing through the front section of the cylinder head obliquely downward, being extended from the position of the attachment of the spark plug 4 by way of a section above an exhaust passage. With this arrangement, it is possible to surely drain water from the upper section of the cylinder head.