Multiple cylinder engine cooling apparatus

Abstract

A multiple cylinder engine cooling apparatus includes a bottom wall of a cylinder head, a lower end of a spark plug inserting cylindrical wall, a lower end of an inlet port, an exhaust port, and a water jacket. A plurality of combustion chamber forming recesses are formed in the cylinder head to line up in a longitudinal direction parallel to an axial direction of a crank shaft. The spark plug inserting cylindrical wall extends from each recess upward in a direction opposite to a combustion chamber. The inlet port extends from each recess laterally in one direction perpendicular to the longitudinal direction. The exhaust port extends from each recess laterally in the other direction. The water jacket is formed in the cylinder head to cool the bottom wall of the cylinder head, the lower end of the spark plug inserting cylindrical wall, the lower end of the inlet port, and the exhaust port. The water jacket includes a first water jacket portion and a second water jacket portion. Cooling water flows in the first water jacket portion in the lateral direction for each cylinder. The second water jacket portion is connected to the first water jacket portion through a narrow channel and guides the cooling water from an interior of the first water jacket portion upward along the exhaust port.