A rev limiter, also known as a RPM limiter or a rev limiter, is a device or a feature in a motorcycle's engine management system that restricts the engine's maximum rotational speed (measured in revolutions per minute or RPM). Its purpose is to protect the engine from operating beyond its safe limits by limiting the RPM to a predetermined value.
The rev limiter is typically implemented through the motorcycle's electronic control unit (ECU), which monitors the engine speed and intervenes when it reaches or exceeds a certain threshold. When the RPM reaches the set limit, the rev limiter cuts off the ignition spark or fuel supply momentarily to prevent the engine from revving any higher.
The specific RPM limit at which the rev limiter activates varies among motorcycles and depends on various factors such as engine design, intended use, and manufacturer specifications. Sports bikes, for example, often have higher rev limits compared to cruisers or touring motorcycles.
Not all motorcycles have rev limiters, particularly older or more basic models. However, most modern motorcycles, especially those equipped with fuel injection and advanced engine management systems, do include a rev limiter as a standard feature. The rev limiter is considered an important safety feature to prevent engine damage caused by excessive RPM, as well as to ensure optimal performance and longevity of the motorcycle's engine.