Profile of the fuel cam has been so designed that fuel is injected in the appropriate timing. In order to minimize distorsion of the camshaft due to high pressure injection, the diameter of the camshaft has been made bigger than that of the former models. The high pressure type fuel injection pump has been employed. Injection characteristic has been improved by high pressure injection as a result of making plunger lifting speed fast and a shortened fuel injection pipe. Aiming at making fuel atomization equal, stable and improving durability of the tip, the inside of the fuel valve nozzle holes has been electrolytic-ground.
7) Cylinder head
The cylinder cover has been reinforced by increased thickness of each part and middle shelf arranged inside water jacket to provide sufficient mechanical stress due to increased combustion pressure. The bottom plate of the cylinder head which forms a combustion chamber wall has been designed thin to reduce thermal stress. Cooling water enters into the cylinder head from bottom side and goes up through center of the mid-shelf after cooling the combustion face. A part of the cooling water is delivered to the exhaust valve cage aiming at equalizing thermal stress. The cylinder head is fitted to the cylinder with eigh sets of hydraulically tightening studs and nuts being aimed at equalizing tightening force and reducing manpower.
8) Intake and exhaust valve
The intake and exhaust valves are of two-valve type i.e., one each valve for one cylinder. Seating faces of both valve and valve seat ring are hardened with Stelite alloy. Not only the exhaust valve, but also the intake valve is equipped with the valve rotator and those are lubricated with exclusive lubricators.
The intake valve, the exhaust valve and the starting valve are of cage type that makes checking and maintenance for the valves possible withoutopening the cylinder head.
