Arlen Ness 81-308

The Sidekick air cleaner is an angled version of our forged billet air cleaners that provides excellent legroom and increased airflow. The performance air filter is made from a black synthetic filter element wrapped in a stainless steel mesh and accepts a clear polycarbonate window to view your intake system in action 

• Angled Shape 
• Patented backing plate technology (US Patent: US 10,851,741 B1)
• High performance Synthetic air filter 
• CNC machined from forged billet aluminum 
• Patent-Pending Oil Catch / Reservoir
• Increase horsepower, torque & mileage 
• Excellent legroom 
• Titanium anodize finish 

FORGED BILLET ALUMINUM BACKING PLATE:

• CNC machined from forged billet aluminum 
• Features Patent-Pending next generation hidden breather technology. Each hidden breather is o-ringed at the heads, passes through the backing plate and exits inside the mouth of the throttle body through proprietary shooter tubes. This eliminates the need for any external hoses or hardware for a virtually closed loop system 
• Radius air inlet for unobstructed airflow
• Specially designed breather bolts are hidden under billet covers for a clean look 
• Eliminates oil blow-bye issues associated with M8 engines by directing any excess breather oil back into the engine 
• Patent-Pending Oil Catch / Reservoir. To ensure no oil saturates the filter and restricts your airflow, the integrated oil catch collects any excess engine oil before it reaches the air filter. Bolt-on design allows oil catch to be serviced when you service the filter element 

PERFORMANCE AIR FILTER:

• Black pre-oiled performance air filter 
• Designed for a clear polycarbonate top 
• Re-usable / washable filter 
• Rain socks / pre-filters and filter service kits available separately 

AIR FILTER HOUSING & CLEAR WINDOW 

• Outer air filter housing is CNC machined from forged billet aluminum 
• Features an angled shape for increased leg clearance and detailed CNC machine work 
• Clear Polycarbonate window allows you to view your engine's intake system in action
• Polycarbonate is hard-coated for long lasting durability and protection from engine oil and UV sunlight   

BACKING PLATE ASSEMBLY (FITMENT SPECIFIC)

08-16 FLT / 16-17 SOFTAIL & FXDLS (FBW)

Backing Plate: 18-200-1B  

Backing Plate Spacers: 18-476-3B (2)

Breather Bolts: 18-472-3 (2) 

O-Rings (6 pack): H-024-6

Throttle Body Gasket: 18-510-2

Throttle Body Hardware, 1/4-20 x 3/4: H-656Z (3) 

Shooter Tubes (2 pack): BT-002 

00-17 TWIN CAM (EXC. FBW)

Backing Plate: 18-201-1B  

Backing Plate Spacers: 18-472-2B (2)

Breather Bolts: 18-472-3 (2) 

O-Rings (6 pack): H-024-6

Throttle Body Gasket: 18-500-5

Throttle Body Hardware, 1/4-20 x 3/4: H-656Z (3) 

Shooter Tubes (2 pack): BT-002 

 91-UP XL SPORTSTER

Backing Plate: 18-202-1B  

Backing Plate Spacers: 18-202-2B (2)

Breather Bolts: 18-202-3 (2) 

O-Rings (6 pack): H-024-6

Throttle Body Gasket: 18-500-5 (2) 

Throttle Body Hardware, 1/4-20 x 3/4: H-656Z (3) 

Shooter Tubes (2 pack): BT-002 

17-2023 M8 MODELS (EXCEPT: 2023 FLHXSE & FLTRXSE)

Backing Plate: 18-203-1B  (No Spacers Needed) 

Breather Bolts: 18-457-4Z (2) 

O-Rings (4 pack): H-024-4

Throttle Body Gasket: 18-457-3

Throttle Body Hardware, 1/4-20 x 1: H-658Z (3) 

Shooter Tubes (2 pack): BT-001 

OIL CATCH ASSEMBLY 

Oil Catch / Reservoir: 18-392-3

Oil Catch Gasket: 18-392-4

Oil Catch Hardware, 8-32 x 3/4: H-619S (2) 

OUTER COVER ASSEMBLY

Sidekick Outer Cover, Black: 81-308-1T

Outer Cover Hardware, 10-24 x 5/8: H-627S (4) 

Polycarbonate Window: 18-960-2

SIDEKICK PERFORMANCE AIR FILTER: 81-300-3

99-17 TWIN CAM (EXCEPT: FBW) 

• 2001-2017 Twin Cam Delphi EFI (Fuel Injected)
• 1999-2006 Twin Cam CV Carb
• *NOTE: Will not fit Fly-By-Wire Models: 08-17 FLT Touring  / 16-17 Softail / 16-17 Dyna FXDLS & 99-01 F.I. FLT 

 08-16 TOURING / 16-17 SOFTAIL  (FBW)

• 2008-2016 FLT Touring / Bagger - FLHT / FLHR / FLHX / FLTR / H-D FL Trike 
• 2016-2017 Softails 
• 2016-2017 Dyna FXDLS 
• 2014-2015 FLSTNSE / 13-14 FXSBSE / 11-12 FLSTSE
• *NOTE: Twin Cam models equipped w/ FBW (Fly-by-Wire or Throttle-by-Wire) 

 91-UP XL SPORTSTER 

• 1991-up Sportster 883 / 1200  with CV Carb or Delphi EFI 

17-2023 M8 MODELS (EXCEPT: 2023 FLHXSE & FLTRXSE)  

• 2017-up FLT Touring / Bagger - FLHT / FLHR / FLHX / FLTR 
• 2018-up Softail Models 

23-26 G2 M8 Touring, 25-26 Softails Models

Touring Models

2026 FLHXLSE CVO Street Glide Limited

2026 FLHXL Street Glide Limited

2026 FLTRXL Road Glide Limited

2026 FLHXSTSE CVO Street Glide ST

2026 FLTRXP Police Road Glide

2024-2026 FLHX Street Glide

2024-2026 FLTRX Road Glide

2023-2026 FLHXSE CVO Street Glide

2024-2026 FLTRXSTSE CVO Road Glide ST

2025 FLHXU Street Glide Ultra

2023-2025 FLTRXSE CVO Road Glide

SOFTAILS Models

2025-2026 FXLRS Low Rider S

2025-2026 FXLRST Low Rider ST

2025-2026 FLFB Fat Boy

2025 FLSTFI Fat Boy Gray Ghost

2025-2026 FLHC Heritage Classic

2025-2026 FXBB Street Bob

2025-2026 FXBR Breakout

TRIKES

2026 FLHLTSE CVO Steet Glide 3 Limited

2026 FLTRT Road Glide 3

2026 FLHLT Steet Glide 3 Limited

  22-UP NIGHTSTER SPORTSTER 

• 2022-up RH975 models 

FITMENT DISCLAIMER

Fitment information is provided as a general reference only and is not guaranteed for any motorcycle, whether stock or modified. Compatibility may vary by year, model, and individual configuration.

Customers are responsible for verifying fitment prior to purchase. House of Harley-Davidson assumes no liability for purchases made based on incorrect or unverified fitment information.

Please TEXT 414-282-2211 with any questions before ordering, or use the chat below.