Patent ID: 7572159

Claim:
In an outboard motor having an external engine cover, the improvement comprising an internal combustion engine installed in an engine compartment defined by the engine cover, said internal combustion engine comprising an engine body having a combustion chamber formed therein, and an intake system having an intake air passage with an intake air inlet and an intake air outlet to carry combustion gas to the combustion chamber, the intake system comprising an intake air routing structure provided inside of the engine cover which is configured and arranged to keep air in the intake air passage separate from ventilation air flowing past the engine in the engine compartment, wherein: the intake air inlet is formed by an air intake duct and is in communication with an exterior of the engine compartment; the engine cover is formed with a receiving ring which is fitted on the air intake duct; the receiving ring and the intake duct cooperate to form an overlapping part in which the receiving ring and the intake duct overlap each other in a direction of flow of combustion air; the overlapping part has a sealing member therein which forms a seal between an exterior of the engine compartment and an interior of the engine compartment; the engine cover is detachably attached to the outboard motor in a manner guided by a stationary positioning member, the sealing member is provided on at least one of the intake duct and the receiving ring, and the internal combustion engine is configured and arranged such that the engine cover is guided by the positioning guide member to cause the receiving ring to fit on the intake duct to form the overlapping part when the engine cover reaches a predetermined position.