US 7,513,811 B2
	Idle exhaust structure for outboard motor
Kentaro Kameoka, Shizuoka-ken (Japan); Masanori Takahashi, Shizuoka-ken (Japan); and Kimitaka Saruwatari, Shizuoka-ken (Japan)
Assigned to Yamaha Hatsudoki Kabushiki Kaisha, Shizuoka (Japan)
Filed on Dec. 28, 2006, as Appl. No. 11/617,528.
Claims priority of application No. 2006-111965 (JP), filed on Apr. 14, 2006.
Prior Publication US 2008/0020659 A1, Jan. 24, 2008
Int. Cl. B63H 21/34 (2006.01)

U.S. Cl. 440—89G  [440/89 J]

10 Claims

1. An idle exhaust structure for an outboard motor including an engine and a cowling for covering the engine from an outside thereof, the idle exhaust structure comprising an idle exhaust passage for discharging exhaust produced during idling to an atmosphere, an expansion chamber formed at a midway portion of the idle exhaust passage, the idle exhaust passage having a plurality of idle exhaust ports formed at a downstream end of the idle exhaust passage and open to the atmosphere, a case that extends longitudinally and is configured to be supported on a hull so as to support the engine on an upper surface side of the case, wherein an expansion chamber case defines the expansion chamber, the expansion chamber case being disposed within a space in an area outside of the case in a horizontal direction and below a portion of the cowling located above the case, wherein the idle exhaust ports are arranged spaced apart from each other in a width direction of the outboard motor.