Moroso Air/Oil Separator - Twin CAM W/V&h Vo2 AIR Cleaner Black — Harley-Davidson (1999-2017)

Moroso air-oil separator for Twin Cam engines running Vance & Hines VO2 air cleaners, designed to filter crankcase vapors, oil mist, and condensation before they re-enter the intake system. Keeps your air filter, throttle body, intake, pistons, and valves clean by preventing oil and carbon buildup.

Features

• Filters crankcase vapors, exhaust vapors, residual oil and moisture
• Two-piece body unscrews for easy cleaning and service
• Does not vent to atmosphere — contains oil in the canister, off your bike and the ground
• Reduces detonation and knock
• Made in the U.S.A.

Specifications

• Brand: Moroso
• Manufacturer Part #: 85717
• UPC: 84663857171
• Length: 9 in
• Width: 6 in
• Height: 5 in
• Weight: 2 lbs

Fitment

Fits Harley-Davidson Twin Cam engines equipped with Vance & Hines VO2 air cleaners.

Frequently Asked Questions

How do I clean the separator?

The two-piece body unscrews easily — no special tools required. Empty the collected vapors and oil, rinse, and reassemble.

Does this vent excess oil to the atmosphere?

No — unlike other breather kits, the Moroso system contains all vapors and oil inside the canister. Nothing vents outside or onto your bike.

Will this reduce engine knock?

Yes. By filtering crankcase vapors before they re-enter the intake, you reduce detonation and knock while keeping combustion cleaner.

Is installation difficult?

The separator plumbs inline with your existing breather system. Installation complexity depends on your current setup — consult the instructions or a shop if you're unsure.

What does it actually catch?

Excess crankcase vapors, unburnt fuel, residual oil, and moisture that normally recirculate into your intake and foul the system.