Patent ID: 7818964
Filing Date: 2010-10-26
Classification: F01N,Y02A

Abstract:
1. An exhaust system for a motorcycle having an engine mounted on a front half of a body frame of the motorcycle in a longitudinal direction thereof, the exhaust system comprising: a plurality of first exhaust pipes extending from exhaust ports of the engine; a collecting section at which the first exhaust pipes are collected together; a second exhaust pipe including a substantially straight portion connected to a downstream side of the collecting section and disposed under a crankcase of the engine; an expansion chamber connected to a downstream side of the second exhaust pipe at a front portion thereof and located under a rear wheel suspension arranged behind the engine as seen in a side view of the motorcycle body; and an exhaust outlet disposed on a most downstream portion of the expansion chamber; wherein the expansion chamber is disposed behind a downward extending portion of an oil pan arranged at a bottom portion of the crankcase, the substantially straight portion is disposed below the oil pan so as to be offset from the downward extending portion in a width direction of the vehicle, an exhaust throttle valve and an exhaust gas sensor are disposed on the substantially straight portion, and the exhaust throttle valve is disposed on an upstream side of the exhaust gas sensor, and a valve shaft of the exhaust throttle valve and a detecting element of the exhaust gas sensor are overlapped with each other as viewed in an axial direction of the second exhaust pipe.