Abstract: An air intake silencer includes an air inlet pipe and at least one tuning tube in fluid communication with the air inlet pipe. A first length and second length of the air inlet pipe and the tuning tube, respectively, are selected to produce one-half wavelength cancellation of a selected frequency of engine noise. A plurality of tuning tubes located in a wrap-around relationship with on another may tune different frequencies of noise in a compact silencing unit. The air inlet pipe and tuning tube may be integrally formed into an air intake manifold that silences one or more engine air intake inlets, and the air intake silencer may be integrated into a motor cover.

Abstract: Disclosed herein is an air silencer comprising a main body including a first member including a first wall partially defining a first plenum area, a second wall partially defining a second plenum area, and a third wall connecting the first and second walls, a second member including a first wall which partially defines a plenum area cooperating with the first plenum area of the first member to define a first plenum chamber, a second wall which partially defines a plenum area cooperating with the second plenum area of the first member to define a second plenum chamber, and a third wall which connects the first and second walls of the second member and is located in spaced relation to the third wall of the first member to define therebetween a narrow passage between the first and second plenum chambers.

Abstract: An exhaust system for a marine jet pump with an internal combustion power head includes a muffler having a muffler inlet in fluid communication with the power head to receive exhaust gases therefrom, and a muffler outlet for emitting the exhaust gases, the muffler further including an exhaust high rise portion being vertically displaced from the inlet and the outlet to prevent the entry into the muffler inlet of water passing into the interior through the muffler outlet.

Abstract: A mounting system for connecting a marine power head having a vertically disposed crankshaft to a jet propulsion unit for isolating operational vibrations includes an adaptor plate, a power head mounting apparatus on the adaptor plate for securing the power head to the plate, and a connecting assembly for connecting the adaptor plate to the jet propulsion unit at at least one point, the connecting assembly including resilient portions to isolate vibrations generated by the power head.

Abstract: A vibration absorbing steering device for an outboard motor having a swivel bracket constructed and arranged for mounting to a transom bracket of a boat and defining a vertical passageway includes a tubular pivot shaft being pivotally engaged in the passageway, an engine mount bracket designed to mount the engine for rotation with the pivot shaft, and a vibration absorbing torque tube for absorbing vibration generated by the engine. The torque tube is vertically disposed within the tubular pivot shaft and is secured at one end to the pivot shaft. A tiller arm has a pivot end attached to the upper end of the torque tube so that the tiller arm is connected to the engine mount bracket through the torque tube, and the torque tube absorbs vibration from the engine which would normally be transmitted through the tiller arm to the operator. In addition to absorbing engine vibration, the present device also permits positive steering control of the motor by manipulation of the tiller arm.

Abstract: Disclosed herein is a marine propulsion device comprising a lower unit including a gear case, a propeller shaft extending in the gear case, an annulus of greater dimension than the propeller shaft and of material weight, and a ring of elastomeric material resiliently connecting the annulus to the propeller shaft is co-axial relation thereto so as to provide for rotation of the annulus in common with rotation of the propeller shaft.