Interactive Exhaust System; General - Buell XB 2008 Series Service Manual

INTERACTIVE EXHAUST SYSTEM

GENERAL

The interactive exhaust system is standard equipment on the
XB12 models only.
See Figure 7-54. An electronically controlled actuator opens
or closes a butterfly valve (1) that controls exhaust flow in a
multi-chamber muffler.
The ECM monitors engine speed and throttle position while
alternating flow paths between the chambers to adjust back-
pressure optimizing torque and horsepower for the riding con-
dition.
For example:
sm00374
8
1. Butterfly valve
2. Exhaust in
3. Valve open (exhaust flow - chamber C)
4. Valve closed (exhaust - chamber A to B to C)
NOTE
1
5
6
7
4
Figure 7-54. Interactive Exhaust System Muffler
1. At low RPM with a wide-open throttle, the valve (1) is
opened to reduce back-pressure so the engine can gain
RPM quickly. The exhaust enters (2) the muffler and flows
(3) through the open valve (1) into chamber C (7) and then
exits (8).
2. In the mid-range, the valve is closed to increase accelera-
tion torque. The exhaust flows (4) through chamber A,
around to chamber B and then through chamber C and
exits.
3. At high RPM, the valve opens again to maximize
horsepower. The exhaust enters (2) the muffler and flows
(3) through the open valve (1) into chamber C (7) and then
exits (8).
4
4
3
4
5. Chamber A
6. Chamber B
7. Chamber C
8. Exhaust exit
1
2
3
4
2008 XB Service: Electrical 7-39
7.14