Yamaha Hatsudoki Kabushiki Kaisha

Yamaha Motor Company Ltd

Koichiro Takeuchi

Noritaka Matsuo

Tokuji Muramatsu

Several embodiments of engine intake systems that improve the charging efficiency by providing a closed branch passage which forms a volume in the intake tract between the throttle valve and the point of discharge into an engine chamber. The illustrated embodiments of the application of this concept is to both four and two cycle engines. In addition, a plenum chamber is illustrated for permitting the effective volume of the branch passage to be increased without unduly increasing its length. The branch passage outlet in certain embodiments is oriented so that its discharge during the intake cycle increases turbulence to improve combustion efficiency.

Intake system for engine

Two embodiments of induction systems for internal combustion engines that improve charging efficiency, particularly at low speeds and throttle openings. In each embodiment a plenum chamber is provided that communicates with the induction system between the throttle valve and the chamber which is served. In each embodiment a control valve controls the communication of the plenum chamber with the induction passage for substantially restricting the communication when the throttle valve of the engine is in its wide open position.

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Iwata, Japan

Koichiro Takeuchi