•  An insert is installed to the exhaust port to improve heat insulation performance and maintain high-temperature exhaust gas. This promotes the earlier activation of the catalyst at cold-engine start.

•  The secondary air port has been equipped on the upper part of the exhaust port, which allows secondary air to flow closer to the combustion chamber.

•  The housing forms the engine outer core with the intermediate housing positioned between the two rotor housings, which are further enclosed by front and rear housings. The components of the housing are positioned precisely using tubular dowel pins.

•  On the front and rear housings are the installation bosses for the stationary gears that regulate the rotational movement of the rotors supporting the eccentric shaft.

•  On the front housing are the bosses for installing the oil pump and the oil strainer.

•  On the intermediate housing are the bosses for the primary injectors, which are placed near the combustion chambers for semi-direct injection. There are also additional bosses for the oil level gauge and the oil filler pipe.

•  The special cast iron side housings are processed with soft-nitriding for improved wear resistance of the rotor friction surfaces. Wall thickness in each area of the side housings has been reduced for weight reduction.

•  Each of the housings are sealed together with rubber seals at the inner and outer circumferences of the water jacket surrounding the rotor friction surface.

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•  The anti-wet port with a projection is located on the bottom edge of the primary port. With the anti-wet port, jet air from the jet air fuel mixing nozzle, located at the primary port outlet of the intake manifold, flows upward, and atomization is accelerated under low load when air intake velocity is slow. At the same time, air current is formed so that the air-fuel mixture flows to the spark plugs. As a result, stable combustion is obtained.

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