Patent ID: 7523735

Claim:
A multiple-cylinder engine for an outboard motor, comprising: an engine body; a crankcase supporting a generally vertically extending crankshaft; at least first, second, third, and fourth cylinders arranged generally vertically, each cylinder extending horizontally outward from the crankcase, and the first, second, third, and fourth cylinders including at least first, second, third, and fourth exhaust ports, respectively, formed in a cylinder head, the engine being configured to have a firing order such that the ignition order of first and second cylinders is not sequential and the ignition order of the third and fourth cylinders is not sequential; at least first, second, third, and fourth exhaust passages communicating with and extending from a downstream end of the first, second, third, and fourth exhaust ports, respectively; and at least first and second joined flow passages the first joined flow passage joining downstream ends of the first and second exhaust passages, the second joined flow passage joining downstream ends of the third and fourth exhaust passages; at least a first expansion chamber communicating with the first and second joined flow passages.