| 摘要 |
The present invention provides a small and light four-stroke cycle internal combustion engine applicable to a compact power working machine. A cylinder head is provided with an ignition plug and an exhaust port with an exhaust valve. A crankcase is fixed to the bottom of a cylinder block are to form a closed crank chamber. On the cylinder block formed are a first port and a second port which are open to a combustion chamber and are opened and closed by a piston, with the second port being communicated with the crank chamber through a communicating passage, the first port being connected to a carburetor, and an air-fuel mixture mixed with lubricating oil being supplied from the carburetor through this first port to the crank chamber.
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