Cylinder head

A cylinder head is provided which can surely return the oil within the sub-cam chamber provided outside the rear end wall into the inside of the cylinder head. In the cylinder head, the front and the rear end wall are formed in parallel; the extension of the camshaft is disposed outside the rear end wall; a separate cover member is mounted on the outside of the rear end wall to form a sub.cam chamber for covering the extension; and an oil-returning hole is formed through the rear end wall so as to return the oil within the sub-cam chamber into the inside of the rear end wall.