Exhaust chamber in motorcycle exhaust system

1. An exhaust chamber for a motorcycle disposed at a location upstream of a muffler in an exhaust passage leading from a combustion engine, which is a member separate from the muffler and comprises:

a chamber inlet pipe protruding in an upstream direction from a chamber body for allowing the exhaust gases to flow therethrough into the chamber body;

a sensor fitted to the chamber inlet pipe for detecting a composition of the exhaust gases within the exhaust passage;

an introducing pipe having an introducing passage defined therein, the introducing pipe being disposed within the chamber body for introducing the exhaust gases, which have flowed through the chamber inlet pipe, into a first expansion compartment of the plurality of expansion compartments in the chamber body;

a catalytic unit disposed within the introducing passage inside the introducing pipe for purifying the exhaust gases entering the first expansion compartment;

the chamber body having a first expansion compartment in fluidic connection with a second expansion compartment and a third expansion compartment in fluidic connection with the second expansion compartment, the third expansion compartment is in fluidic connection with a resonance compartment, wherein the first expansion compartment shares a heat exchanging partition plate with respectively the resonance compartment and the third expansion compartment to reduce heat in the first expansion compartment and the catalytic unit;

a chamber outlet pipe having an outlet passage defined therein for discharging exhaust gases from the chamber body; and

an exhaust control valve disposed in the chamber outlet pipe for adjusting a sectional area of the outlet passage inside the chamber outlet pipe,

wherein a rear end portion of the chamber outlet pipe is connected with a front end of the muffler.

2. The exhaust chamber for the motorcycle as claimed in claim 1 wherein the chamber outlet pipe protrudes rearwardly from a rear end portion of the chamber body.

3. The exhaust chamber for the motorcycle as claimed in claim 1 wherein the chamber outlet pipe includes an exhaust cowling overlaying the chamber outlet pipe and the exhaust control valve.

4. The exhaust chamber for the motorcycle as claimed in claim 1 , wherein a chamber cowling is mounted on an exterior of the chamber body with a gap configured to direct a flow of air to provide a heat exchange with the chamber body on a first side of the motorcycle and on an opposite second side of the motorcycle while protecting the rider from contact with the exhaust chamber.