A motorcycle exhaust servo, also known as an exhaust valve servo or exhaust servo motor, is a component found in some motorcycles equipped with electronically controlled exhaust systems. Its primary function is to control the operation of an exhaust valve or flap within the exhaust system.
The exhaust servo motor is typically connected to the exhaust valve through a mechanical linkage or cable. It receives signals from the motorcycle's engine control unit (ECU) or other control modules, instructing it to open or close the exhaust valve based on various factors such as engine speed, throttle position, and other operating parameters.
The main purposes of an exhaust servo are as follows:
Emissions Control: The exhaust valve controlled by the servo helps regulate the flow of exhaust gases. By adjusting the exhaust valve position, the motorcycle's ECU can optimize the backpressure in the exhaust system, which affects engine performance and emissions. Opening the valve allows for increased exhaust flow and can enhance high-end power, while closing the valve restricts flow and can improve low-end torque and reduce noise.
Noise Reduction: By manipulating the position of the exhaust valve, the servo can help attenuate exhaust noise. During lower engine speeds or when a quieter operation is desired, the exhaust valve may be partially closed to direct exhaust gases through a longer or more restricted path, reducing the overall noise level.
It's worth noting that not all motorcycles have exhaust servos, as their presence depends on the specific model, manufacturer, and exhaust system design. Some motorcycles use other mechanisms, such as fixed-position exhaust valves or aftermarket exhaust systems that do not require servo-controlled valves.