PURPOSE: To attain stratification improved by supplying a mixture, jetted from a mixture supply port, to about a spark plug, and suppressing fuel from adhering to a cylinder peripheral wall and a piston top surface, in a structure wherein the mixture supply port is opened to a cylinder bore central part in the upper surface of a combustion chamber to provide a timing valve in this port.
CONSTITUTION: A timing valve 15 of a mixture supply port 7 is formed of a poppet valve, and also providing the first/second guide parts 23, 24 in a wall surface continued to a seating part in the periphery of this valve. A jetted mixture is guided in a direction of the axial line of a cylinder by the first guide part 23 to the halfway of lifting the timing valve 15, and a direction of jetting the mixture is spread to a peripheral side of the cylinder by the second guide part 24 in a side of large lifting the timing valve.
MARUHARA MASASHI
TABATA MICHIHIKO
TANAKA TATSUYA
