Air Filter Cleaning – Replacement Guide for 2021 Honda CRF450R

Shop parts for a 2021 Honda CRF450R Dirt Bike.

The 2021 Honda CRF450R features a revolutionary upside-down air filter placement, designed to prevent dirt buildup on the filter and improve airflow. Owners should note that the filter sits above the intake, which is different than previous models and requires specific attention during maintenance—this design results in less dirt accumulation and easier access for cleaning and replacement compared to older CRF450Rs–a significant upgrade in airbox efficiency.

Unique Air Filter Design for the 2021 CRF450R

  • The OEM air filter features dual-stage open-pore foam.
  • Upside-down filter placement increases protection and airflow.
  • Larger filter surface compared to previous models.
  • Easy-to-install replacement parts enabled by a rubber O-ring-sealed aluminum cage (in Twin Air PowerFlow kits)
  • Backfire sealing ring improvement with lightweight aluminum.

Tools – Supplies You Will Need

  • Philips screwdriver
  • Clean rags
  • Foam-specific air filter cleaner
  • Foam filter oil
  • Motocross air filter grease
  • Replacement air filter (OEM dual-stage or compatible aftermarket options like Twin Air)

Air Filter Removal Steps

  • Remove seat by loosening seat bolts.
  • Access the airbox from above.
  • Carefully unscrew the filter retaining bolt and lift out the air filter cage and element.

Cleaning Procedure

  • Tap the filter to remove loose debris; do not bang against hard surfaces.
  • Apply foam filter cleaner and gently massage out all dirt and oil, then rinse thoroughly with warm water.
  • Allow the filter to dry completely—do not use compressed air or heat sources.
  • Inspect for tears or damage; replace if necessary.
  • Apply foam filter oil evenly and knead thoroughly to ensure all pores are penetrated.
  • Grease the filter sealing surface to ensure maximum contact with the airbox.

Reinstallation Steps

  • Align filter cage securely in the airbox.
  • Seat the filter, ensuring perfect perimeter contact.
  • Replace and tighten the retaining bolt by hand–do not overtighten.
  • Reinstall seat and check for proper fitment.

Replacement Guide

  • Replace the filter if it shows signs of significant wear, damage, or reduced elasticity.
  • For upgrades or racing, consider the PowerFlow kit which utilizes a larger filter surface and aluminum cage for enhanced airflow and protection.

Model-Specific Maintenance Notes

  • The 2021 Honda CRF450R's airbox is increased to four liters on the clean side, allowing better filtration and less clogging.
  • New mounting style promotes a quicker removal and installation process.
  • Works Edition variant includes a Twin Air filter stock.

Regular maintenance & proper air filter care are crucial to maximizing the performance and longevity of your 2021 CRF450R. If you notice loss of power, increased engine noise, or more frequent clogging, inspect & clean immediately —always maintain a fresh, oiled filter for best results.

Related Shopping Categories

Shop Air Filters for a 2021 Honda CRF450R Dirt Bike.

Shop Air Filter Oil for a 2021 Honda CRF450R Dirt Bike.

Shop Air Box Covers for a 2021 Honda CRF450R Dirt Bike.

Shop Tools for a 2021 Honda CRF450R Dirt Bike.

Shop Intake Parts for a 2021 Honda CRF450R Dirt Bike.

Disclaimer: This guide is provided for general informational purposes only and is not intended to replace your motorcycle's official owner's manual. Always refer to your manufacturer's documentation for model-specific instructions, torque specifications, safety procedures, and maintenance requirements. If you are unsure or inexperienced, consider seeking assistance from a qualified mechanic or technician.