To provide a four cycle engine provided with an internal EGR system capable of making internal EGR amount and timing of internal EGR correspond to engine operation conditions and a valve opening condition of a suction valve freely and controlling to a proper value for reducing amount of NOx (nitrogen oxide) generation without reducing engine performance.

In this four cycle engine equipped with the internal EGR system, the suction valve is constituted to open the valve in two lift forms of main lift including fully opening of the suction valve and sublift being smaller than the main lift earlier than start of the main lift. A suction control valve for changing suction passage area by opening and closing a suction passage at the time of sublift of the suction valve is provided in the suction passage. The amount of EGR fed into the suction passage from the inside of a combustion chamber is adjusted by opening and closing the suction control valve at the time of sublift.

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