ENGINE STRUCTURE

PURPOSE:To make a cylinder head common to various kinds of engines having three intake and exhaust valves in total, to reduce the manufacturing cost of engines, by arranging passages and holes which are formed in the cylinder head, corresponding to a cylinder block, in point-symmetry with respect to the center of the cylinder head. CONSTITUTION:At a lower section deck surface 1A of a cylinder head 1, three, in total, of ports P1 through P3 are opened within a combustion recess 2, one being on one side of the center line LC in the crank axial direction and two being on the other side of the center line LC, and a spark plug hole 3 is formed at a position which is substantially equidistant from the center of the ports. Further, holes and passages such as, cooling water passages W, tension bolt holes (t) and the like are all arranged point symmetry with respect to the center O of the cylinder head 1. With this arrangement, it is possible to cope with the case of two intake valves or the case of two exhaust valves, by reversing the mounting positions of intake and exhaust manifolds, and therefore, it is possible to use the cylinder head to various kinds of engines.