| 摘要 |
An intake port for guiding new intake air into a combustion chamber of a cylinder and an exhaust port for discharging exhaust combustion gas from the combustion chamber to the outside, are formed in a cylinder head mounted on the cylinder for housing a piston movably in a reciprocating manner. The intake port is opened/closed by intake valve, and the exhaust port is opened/closed by exhaust valve. Openings of the intake and exhaust ports at the combustion chamber side are formed to be displaced toward central portion of the combustion chamber. An inclining angle of the intake valve formed between the central axis of the intake valve and the central axis of a cylindrical bore of the cylinder is set larger than an inclining angle of the exhaust valve, formed between the central axis of the exhaust valve and the central axis of the cylindrical bore of the cylinder, and a bulge portion is formed on the inner surface of the intake port, oppositely to a valve guide for guiding movably the intake valve of the intake port.
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