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The K&N E-3040 is a washable reusable oval air filter that replaces the element in RK-3929 custom air cleaner assemblies on select 2004-2021 Harley-Davidson Sportster models. It delivers higher airflow for gains in horsepower and acceleration while protecting your engine with four-layer cotton gauze filtration. Covered by K&N Million Mile Limited Warranty this direct-fit filter maintains peak performance over time.
Key Features
- Direct RK-3929 Replacement: Exact oval shape with 5 in x 3 in outside diameter 2.5 in inside diameter and 1.25 in height for seamless fit.
- Four-Layer Cotton Gauze Media: Traps dirt and debris for engine protection without restricting flow.
- High Airflow Design: Boosts horsepower and quicker throttle response through increased air volume into the engine.
- Four layers of oiled cotton gauze pleated over steel mesh for high flow and dirt-holding capacity.
Fitment
| Fitment Status | Universal or dimensional product |
|---|---|
| Required Verification | Exact dimensions, media, connection, mounting interface, and companion part number |
Specifications
| Brand | K&N Engineering |
|---|---|
| Manufacturer Part Number | E-3040 |
| Product Type | Air Filters - Drop In |
| Fitment Type | Universal |
| Condition | New |
What's Included
One new K&N air filters - drop in identified by manufacturer part number E-3040. Hardware, adapters, clamps, hoses, filters, and service supplies are included only when stated for this exact product.
About K&N Engineering
K&N develops reusable air filtration, intake, oil filtration, fuel filtration, and related performance products for vehicle-specific and dimensional applications.
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Frequently Asked Questions
How do I confirm K&N E-3040 fits my setup?
Match every listed dimension, flange or thread size, media type, mounting interface, and companion component. A similar shape or outside dimension alone does not confirm compatibility.
Is K&N E-3040 washable and reusable?
Serviceability depends on the exact media used for this part number. Follow the K&N cleaning and oiling directions for this filter and never apply oil to media specified as dry.
What should be checked after installing K&N E-3040?
Verify seals, clamps, fasteners, hoses, sensors, wiring, and surrounding clearance as applicable. Check for leaks or contact, then follow the manufacturer service and reinspection schedule.
Installation Instructions
- Remove old element from RK-3929 housing and drop in E-3040 no modifications needed
- Compatible with stock RK-3929 hardware and chrome lid
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