Patent ID: 7624842

Claim:
An exhaust system comprising: an engine; an exhaust pipe connected to the engine; a muffler connected to the exhaust pipe, wherein the muffler has an inner cylinder disposed in an outer cylinder, and is separated into a plurality of expansion chambers with partitions, wherein the end of the exhaust pipe extends into a central portion of the outer cylinder and faces the partitions which divide an inside of a main body of the muffler into a first expansion chamber on a front side of the partition and a second expansion chamber on a rear side of the partition; a muffling member having multiple through holes placed between the end of the exhaust pipe and the partitions; a communicative passage for communicatively connecting the expansion chambers is formed between the outer cylinder and the inner cylinder; a plurality of weight reducing holes are formed in a contacting part where the inner cylinder contacts the outer cylinder except for a part constructing the communicative passage; and both edge portions of a part of the inner cylinder constructing the communicative passage contact the outer cylinder at least over a predetermined length in a longitudinal direction of the inner cylinder and are welded thereto.