Patent ID: 6761239
Filing Date: 2004-07-13
Classification: F01N,F02B,F02D,Y02T

Abstract:
An exhaust system of a motorcycle which has a body frame including a head pipe supporting a front wheel of the motorcycle, a main frame which branches, at a position immediately behind the head pipe, into a pair of lateral main frame members that extend obliquely rearward and downward, a center frame including a pair of lateral center frame members connected to the rear ends of the main frame members so as to extend substantially upright, and a pair of lateral seat rails extending obliquely upward and rearward from end portions of the center frame members, and in which a swing arm supporting a rear wheel of the motorcycle is supported swingably and resiliently to the body frame by a rear shock absorber, and a four-stroke-cycle multi-cylinder engine is mounted on to the body frame,said exhaust system comprising: exhaust pipes leading from the respective cylinders of the engine, said exhaust pipes being collected as a single exhaust pipe collection unit; a muffler to which said exhaust pipe collection unit is connected; an interconnecting pipe section through which the exhaust pipes and the muffler are operatively connected; and an exhaust control system for controlling pulsation of an exhaust gas, said exhaust control system including a valve mechanism mounted to the interconnecting pipe section so as to vary a cross-sectional area of an exhaust passage and a drive unit for operating the valve mechanism, said valve mechanism being located at a position under the swing arm behind the main frame within a triangular zone formed between the rear shock absorber and a bank line that indicates a maximum bank angle of a body of the motorcycle.