Moroso Air/Oil Separator - M8 W/Stock & SE AIR Cleaners Polished — Harley-Davidson (2017-2020)

Moroso air-oil separator for Milwaukee-Eight engines with stock or S&E air cleaner setups, designed to filter crankcase vapors, oil mist, and condensation before they enter the intake system. Keeps the breather system functional while protecting your engine from oil buildup and carbon deposits on valves, pistons, and intake components.

Features

• Filters crankcase vapors, fuel residue, and moisture from breather system
• Two-piece design unscrews for easy cleaning and service
• Closed-loop system—does not vent to atmosphere, keeping oil contained and off the ground
• Reduces detonation and knock from oil-contaminated intake charge
• Made in the U.S.A.

Specifications

• Brand: Moroso
• Manufacturer Part #: 85722
• UPC: 84663857225
• Length: 9 in
• Width: 6 in
• Height: 5 in
• Weight: 2 lbs

Fitment

Fits Harley-Davidson Milwaukee-Eight (M8) engines equipped with stock or S&E air cleaners.

Frequently Asked Questions

Why do I need an air-oil separator if my breather system already works?

Factory breather systems vent crankcase oil and vapors back into the intake, which fouls your filter, throttle body, and valves. This separator filters those contaminants before they re-enter the engine.

Does this vent to the atmosphere like other catch cans?

No—this is a closed-loop system. Oil and vapors collect in the canister instead of venting to the air, keeping oil off your bike and the ground.

How often do I need to empty or service it?

The two-piece design unscrews for easy cleaning. Service interval depends on riding conditions and engine wear—check monthly and empty as needed.

Will this work with my S&E air cleaner?

Yes—this separator is designed for both stock and S&E air cleaner configurations on M8 engines.