Exhaust structure of straddle-type vehicle, and vehicle incorporating same

A straddle-type vehicle comprising:

• an engine;
• an exhaust pipe extending from the engine;
• and
• a muffler connected to said exhaust pipe;
• wherein said muffler comprises:
• an outer tube;
• a noise-damping material provided on an inner circumference of said outer tube;
• a body end member provided at a downstream end of said outer tube;
• a first separator and a second separator disposed in said outer tube and define expansion chambers in said outer tube, said second separator being disposed between the first separator and the body end member;
• and
• a communication pipe which penetrates said first separator and provides a communication passage between said expansion chambers;
• wherein:
• said second separator and said body end member define a resonator chamber in a downstream portion of said outer tube;
• a circumferential portion of said resonator chamber is surrounded by said noise-damping material;
• and
• the resonator chamber only communicates with one of the expansion chambers located closest to said body end member and does so through an opening defined in the second separator, the opening having a diameter which is less than half of an inner diameter of the communication pipe.

A muffler comprising

• an outer tube;
• an inner tube provided inside said outer tube;
• a noise-damping material disposed between said outer tube and said inner tube,
• a body end member provided at a downstream end of said outer tube;
• a first separator and a second separator disposed in said outer tube and which define expansion chambers in said muffler;
• wherein:
• said second separator and said body end member define a resonator chamber in a downstream portion of said outer tube;
• a circumferential portion of said resonator chamber is filled with said noise-damping material;
• a volume of the resonator chamber is less than half of the volume of any of the expansion chambers;
• and
• the resonator chamber only communicates with one of the expansion chambers.