Abstract: Several embodiments of outboard motors embodying four-cycle engines having an oil tank that is contained within the drive shaft housing and which is surrounded at least in part by a water cooling jacket for maintaining the oil at an acceptable temperature. The oil tank is formed with a cavity through which an exhaust pipe passes and the area between the exhaust pipe and the oil tank forms, in at least some embodiments, an expansion chamber for silencing the exhaust gases. At least in part of the exhaust pipe and/or expansion chamber is also cooled by a water cooling jacket.

Abstract: An arrangement for insuring that an internal combustion engine of an outboard motor will operate efficiently under all trim adjusted conditions of the outboard motor. The trim angle is sensed and an engine system such as the timing is adjusted to provide good running in response to the trim condition. Additionally, an embodiment is disclosed wherein the ignition timing is also adjusted during initial starting so as to provide adjustment of the ignition in response to both the starting condition and the trim condition.

Abstract: A synchronizing mechanism for synchronizing a plurality of throttle valves that employs a single coupling member that couples slave butterfly valves to a directly operated butterfly valve for synchronizing all of the butterfly valves simultaneously.