Breather Kits & Parts

Welcome to our Harley Breather Kits & Parts category — your trusted destination for premium breather systems, crankcase ventilation components, and upgrade parts tailored for Harley-Davidson motorcycles. Whether you ride a Twin-Cam, M8, Evolution, or custom-built bike, a proper breather kit is essential for engine health, cleaner operation, and improved performance.

What Is a Breather Kit — And Why It Matters

• Maintains Proper Crankcase Ventilation. The breathing system (also known as crankcase ventilation) allows built-up blow-by gases — a mix of combustion gases, oil vapors, and moisture — to safely escape the engine. Without proper ventilation or with a clogged breather, pressure can build up inside the crankcase, leading to leaks, oil seepage, sludge buildup, and reduced engine efficiency.

• Reduces Oil Contamination & Intake Fouling. Many aftermarket breather kits and external breathing systems (EBS) reroute hot, oily crankcase vapors away from the air-cleaner and combustion intake. This prevents oil mist from being drawn back into the engine, which can cause fuel-air mixture issues or even detonation on certain builds. 

• Promotes Engine Longevity & Clean Operation. A properly designed breather system helps maintain slightly negative crankcase pressure, reducing stress on gaskets, seals, and internal components. It also helps keep internal engine surfaces and the air-intake path cleaner, which contributes to smoother performance and easier maintenance.

• Important for Performance Builds & Custom Engines. Whether you're building a high-performance Twin-Cam, M8 or custom chopper, external breather kits are often recommended to manage increased blow-by and keep the intake system oil-free — a critical factor for reliability, especially under heavy throttle or long rides.

Our top 2 choices for Harley M8 models would be the Trask Assault External Breather or HPI External Breather option.