Air Filter Cleaning & Replacement Guide for 2018 KTM 85SX

Shop parts for a 2018 KTM 85SX Dirt Bike.

Maintaining a clean air filter is essential to keeping your 2018 KTM 85SX running at peak performance. KTM recommends cleaning the air filter before every race or any time dust has visibly accumulated. The unique airbox design of the 85SX allows for tool-free air filter changes–a feature that makes routine maintenance quick and rider-friendly.

Preparation – What You Need

  • Biodegradable or petroleum-based air filter cleaner (match to your filter oil type)
  • Air filter oil (choose the type you normally use, check your owner's manual if uncertain)
  • Clean water for rinsing
  • Nitrile or latex gloves
  • Grease for the filter rim (standard practice on KTM models)
  • Spare air filter (optional, speeds up the process between rides)

Removing the Air Filter

  • Remove the seat. On the 2018 KTM 85SX, use the two side bolts to unfasten and slide the seat back. No specialized tools required; just locate the seat's mounting bolts on each side and remove.
  • With the seat off, grasp and pull off the airbox cover. It attaches with grommets for fast, tool-free access.
  • Release the tabs holding the air filter cage in place, then carefully remove the filter and cage assembly.

Cleaning the Filter

  • Drop the dirty air filter into a cleaning solution. Let it soak for 10–15 minutes to loosen dirt and oil.
  • Gently squeeze (do not twist) and massage the cleaner through the filter to break up dirt. Repeat if needed until clean.
  • Rinse thoroughly with clean water until no dirt or cleaner remains. Squeeze out excess water–avoid wringing to prevent filter damage.

Inspection

  • Inspect the filter carefully for any holes, tears, or weak spots. Damage can allow dirt into the engine, causing harmful wear or catastrophic failure. Always discard and replace damaged filters immediately.

Oiling and Installation

  • Apply air filter oil thoroughly, ensuring every part of the foam is saturated. Squeeze out excess oil so it doesn't drip but remains tacky.
  • Add a light coat of grease to the rim of the filter to improve the seal against the airbox. This is especially important on KTM models to keep fine dust out of the intake tract.
  • Reinstall the filter and cage assembly in the airbox, making sure it seats evenly and the tabs click securely.
  • Replace the airbox cover and reinstall the seat, tightening both bolts securely.

Special Notes for 2018 KTM 85SX Owners

  • The tool-free airbox cover and side-mounted seat bolts are unique to this generation of KTM 85SX models, streamlining filter access for trackside maintenance.
  • KTM specifies servicing the air filter before every race, highlighting the bike's high airflow sensitivity and focus on performance.
  • Avoid over-oiling–excess oil can restrict airflow, while too little reduces filtration. Consistent maintenance helps preserve your engine's longevity and maximize power output.

When to Replace Your Air Filter

  • If the filter is torn, clogged beyond cleaning, or showing signs of deterioration, replace it immediately.
  • Frequent racers should keep at least one spare filter on hand for quick swaps between motos or practice sessions.

Trust MotoSport for OEM and aftermarket 2018 KTM 85SX air filters, cleaners, and pre-oiled options to keep you ready for the next ride.

Related Shopping Categories

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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.