OIL RETURNING STRUCTURE IN ENGINE

摘要

PROBLEM TO BE SOLVED: To rapidly heat up oil and to return the oil from a valve system chamber to a crank chamber in a simple structure allowing avoidance of engine enlargement and weight increase, in an engine in which a cylinder head having a downwardly opened exhaust port is joined to a cylinder block having a cylinder bore tilting downwardly from the cylinder head side and a head cover forming a valve system chamber for storing a valve system mechanism between it and the cylinder is joined to the cylinder head. SOLUTION: An oil returning passage 107 for returning the oil from the valve system chamber 79 to the crank chamber 42 in a crank case 40 is provided in the lower part of the cylinder head 39 by surrounding a part of an exhaust port 71.