Abstract: An engine control system wherein the engine throttle valve is maintained in a substantial partially opened position at idle and the desired idle speed is maintained by controlling the spark advance. A lost motion connection connects the operator engine speed control with the throttle control so that when the operator speed control reaches a pick up position, the lost motion will be taken up and normal throttle opening will occur. This improves transient running. The system includes arrangements for detecting wear or other changes in the operative condition and compensating for it.

Abstract: A number of exhaust systems for watercraft propelled by a propulsion unit contained within a tunnel formed in the underside of the hull. This tunnel has an opening through the side of the hull and exhaust gases are delivered to the tunnel from the engine through an exhaust system having an exhaust opening communicating with the tunnel. Various flow controlling arrangements are provided for controlling the flow through one or all of the openings so as to assist in exhaust silencing without significantly increasing back pressure.

Abstract: A throttle linkage system for synchronizing the movement between a plurality of throttle valves journaled in throttle bodies affixed to a common member that includes a link that has the same coefficient of thermal expansion as the member to which the throttle bodies are connected so as to avoid synchronization problems due to different thermal expansions. In addition, the linkage system is such that it accommodates manufacturing variations from the more remotely positioned throttle valves by providing a structure for permitting relative movement.

Abstract: An outboard motor for mounting on the transom of a boat, has a horizontal engine and output shaft, an exhaust system having a high speed exhaust discharge includes a horizontal portion and a vertical portion having an enlarged cross sectional water jacketed muffler within a water chamber having a retaining wall defining the water level, and a low speed exhaust discharge extending from the muffler into a conduit having an end disposed below the water level of said water chamber, a low speed exhaust gas expansion chamber receiving exhaust gas and expelling same to the atmosphere. The outboard motor is tiltable and provides an enclosure for the engine area including a cowling, hood, and moveable hood section and a sleeve between the moveable hood and engine to perfect enclosure during tilting.

Abstract: An exhaust system for a small watercraft that includes a water trap device for precluding water entering the exhaust system if the watercraft becomes inverted from entering the engine through the exhaust system. Coolant from the engine is delivered to a cooling jacket that encircles the entire exhaust system and is introduced into the exhaust gases downstream of the water trap so that in the event of inversion and righting the engine coolant will also not enter the exhaust system. This also provides protection for catalyzers in the exhaust system.