A motorcycle crankcase breather, also known as a crankcase ventilation system or PCV (Positive Crankcase Ventilation) system, is a component that helps regulate the pressure and airflow within the engine's crankcase. Its primary function is to remove excess gases, contaminants, and moisture from the crankcase and direct them back into the combustion process or vent them to the atmosphere.
The crankcase breather serves several important purposes:
Pressure regulation: During the engine's operation, combustion gases can escape past the piston rings and enter the crankcase, creating pressure. The breather system allows this pressure to be vented, preventing a buildup that could cause leaks or damage to seals and gaskets.
Contaminant removal: The crankcase breather system helps remove contaminants, such as oil vapor, unburned fuel, and combustion by-products, from the crankcase. These contaminants can accumulate over time and contribute to sludge formation or increase oil viscosity, potentially leading to engine damage or reduced performance.
Moisture control: Moisture can accumulate inside the crankcase due to condensation or other factors. The breather system helps remove this moisture, preventing it from causing corrosion or diluting the engine oil.
The design of crankcase breathers can vary depending on the motorcycle's make, model, and engine configuration. In some motorcycles, the breather system is connected to the intake manifold, allowing the excess gases to be reintroduced into the combustion process for efficient burning. This is typically achieved through a breather hose or tube that connects the crankcase to the intake system.
In other cases, motorcycles may feature a closed-loop system, where the excess gases are captured in a separate container, commonly known as a catch can or breather box. This container collects the gases and separates the oil and contaminants before allowing clean air to be recirculated back into the engine or vented to the atmosphere.
Regular maintenance and inspection of the crankcase breather system are essential to ensure its proper functioning. Clogged or malfunctioning breathers can lead to increased crankcase pressure, oil leaks, reduced engine performance, or other related issues.