Pistons, Connecting Rods and Cylinders

Three piston rings are fitted in the corresponding grooves in the upper third of each piston. They press against the cylinder wall. The two upper piston rings prevent combustion gases from passing from the combustion chamber down into the crankcase, while the lower oil control piston ring prevents excessive oil from passing from the crankcase into the combustion chamber.

The cylinders, in which the pistons move up and down, are located in the cast iron engine block. The inner cylinder walls are finished with a cross-hatch honing pattern. The cylinder walls must not be completely smooth, otherwise the oil required for lubrication will not be retained on them. During engine repair, the cylinder bore surfaces may be re-honed up to two times.