| 摘要 |
PROBLEM TO BE SOLVED: To reduce blow-by loss of fuel by separating mixture into lean and rich mixtures utilizing inertia of fuel particles flowing through a scavenging passage. SOLUTION: A scavenging passage is provided with an auxiliary scavenging passage 12 faced to an exhaust port while opening to a cylinder inner wall surface part arranged on a front surface of the exhaust port. A main scavenging passage 10 is branched from a branch part 9 arranged on the way of a connecting passage 8 from a crank chamber 3, and the connecting passage 8 is connected to the auxiliary scavenging passage 12. Connecting passage parts arranged on just front and rear parts of the branch part 9 are connected to each other so as to fill fuel particles flowing through the connecting passage part arranged on just front part of the branch part 9 into the connecting passage part arranged on just rear part of the branch part 9 by inertia. In a part farthest from an exhaust port, rich mixture flows toward a combustion chamber direction. In a part nearest from the exhaust port, lean mixture flows toward the combustion chamber direction.
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