K&N Universal Custom Air Filter – Oval Shape 9.313in OD / 2.375 Height

SKU: E-3988 | UPC: 024844366818

K&N Universal Custom Air Filter – Oval Shape 9.313in OD / 2.375 Height for Harley-Davidson Sportster 2004-2022

K&N E-3988 is a washable reusable oval air filter designed as a direct replacement for RK Series air cleaner assemblies on Harley-Davidson Sportster motorcycles from 2004 to 2022. This high-flow filter increases horsepower and acceleration by allowing greater airflow while maintaining strong filtration to protect your engine. Crafted with cotton gauze media and precise dimensions of 9.313in outer diameter 8.25in inner diameter and 2.375in height it fits perfectly in RK-3930 RK-3113 and compatible assemblies.

Key Features

• High Airflow Design: Boosts horsepower and rate of acceleration through increased air volume for responsive throttle and quicker rides on Sportster models.
• Exceptional Filtration: Cotton gauze media traps dirt and debris effectively to safeguard engine components during long rides.
• Washable and Reusable: Clean with K&N cleaning kit and re-oil for repeated use saving money over disposable filters.
• Million Mile Limited Warranty: Backed by K&N lifetime guarantee covering defects for peace of mind.
• Precise Fit Specifications: Oval shape with 9.313in flange OD 8.25in flange ID 2.375in height and centered rubber flanges drops into RK Series assemblies without modifications.

Product Notes

• Pre-oiled and ready to install out of the box.
• Service every 50000 miles under normal riding conditions or more frequently in dusty environments.
• Ships in protective box measuring 9.45in x 9.21in x 3.98in.

Installation Notes

• Professional installation recommended.
• Remove old filter from RK Series housing and insert E-3988 directly no tools required for most setups.
• Compatible with stock RK backing plates and hardware on Sportster models.

This Part Fits

Year	Make	Model	Submodel
2004-2022	Harley-Davidson	Sportster	XL883
2004-2022	Harley-Davidson	Sportster	XL883C Custom
2004-2022	Harley-Davidson	Sportster	XL883L SuperLow
2004-2022	Harley-Davidson	Sportster	XL883N Iron
2004-2022	Harley-Davidson	Sportster	XL1200
2004-2022	Harley-Davidson	Sportster	XL1200C Custom
2004-2022	Harley-Davidson	Sportster	XL1200N Nightster
2004-2022	Harley-Davidson	Sportster	XL1200R Roadster
2004-2022	Harley-Davidson	Sportster	XL1200T SuperLow
2004-2022	Harley-Davidson	Sportster	XL1200X Forty-Eight

Why Choose K&N?

• Proven leader in high-performance air filtration for motorcycles since 1969.
• Engineered for real-world power gains and engine protection on Harley models.
• Precision-molded rubber flanges ensure airtight seal in RK Series housings.

Frequently Asked Questions

• Q: Does E-3988 fit all 2004-2022 Harley Sportster models?
  A: Yes it replaces the filter element in K&N RK Series air cleaners like RK-3930 and RK-3113 used on XL883 and XL1200 Sportster variants confirm your assembly matches the 9.313in OD flange.
• Q: What material is used in this filter?
  A: Four-ply cotton gauze pleated media pre-oiled for instant filtration and high airflow oiled cotton traps fine particles better than paper.
• Q: What does the warranty cover?
  A: K&N Million Mile Limited Warranty protects against material and workmanship defects when cleaned and re-oiled per instructions.

Shipping & Handling

• Method: UPS Ground or USPS Priority
• Availability: In stock – ships same or next business day
• Packaging: Compact box 9.45in x 9.21in x 3.98in
• Weight: 1.2 lb (0.5 kg)