| 摘要 |
A four cylinder four cycle spark ignition engine has oblong pistons each mounted to reciprocate within an oblong cylinder. Each piston is elongated in a direction parallel to the axis of the crankshaft and is provided with piston rings which have sliding contact with the surface of the oblong cylinder. Each piston ring is split at one side, and the free shape thereof prior to installation is such as to give superior results after installation when the engine is operated at high speed and high performance.
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