How to Change the Coolant in a 2021 Husqvarna FX350

Shop parts for a 2021 Husqvarna FX350 Dirt Bike.

Performing a coolant change on your 2021 Husqvarna FX350 is a critical maintenance task to ensure the longevity and optimal performance of your engine. This exclusive MotoSport guide gives you clear, step-by-step instructions specific to your bike, along with important notes unique to the FX350.

Tools – Materials Needed

  • Socket wrench set (notably 10 mm)
  • New pre-mixed motorcycle coolant formulated for aluminum engines
  • Drain pan
  • Funnel
  • Soft cloths for cleanup

Step 1 – Preparation

  • Ensure the engine is completely cool to avoid burns.
  • Stand the motorcycle upright on level ground for accurate draining and refilling.
  • Remove any plastic panels or guards that block access to the coolant cap or drain bolt (if needed).

Step 2 – Access the Radiator Cap

  • Locate and slowly remove the radiator cap to release any remaining pressure in the cooling system. Do this before draining the coolant to prevent spills.

Step 3 – Draining the Coolant

  • Locate the coolant drain bolt on the water pump cover. On KTM and Husqvarna engines, the bolt is marked with a copper washer.
  • Position the drain pan under the bolt. Then, remove the drain bolt to allow coolant to flow out completely from the system and radiators.
  • Inspect the copper washer for wear—if it looks flattened or damaged, replace it.

Step 4 – Flushing (Optional but Recommended)

  • For thorough maintenance, refill the system with distilled water, reinstall the cap, run the engine briefly, then drain again. Repeat until the runoff is clear, especially if the old coolant looked dirty or rusty.

Step 5 – Refilling with New Coolant

  • Install and torque the drain bolt to spec (typically 10 Nm / 7.4 lbf–ft).
  • Slowly pour the new coolant into the radiator until it reaches the bottom of the filler neck. The FX350 radiator fills from the right side.
  • Reinstall the radiator cap securely.

Step 6 – Bleeding Air from the System

  • Start the engine and let it idle with the radiator cap off. Watch for air bubbles rising out—this indicates trapped air is escaping.
  • Once the bubbling subsides and coolant level drops, top it off and replace the cap.
  • After riding and cooling, re-check the coolant level and add more if needed.

Additional Notes for 2021 Husqvarna FX350 Owners

  • The 2021 FX350 features a high-revving engine with close tolerances; regular coolant changes are essential to prevent heat-related wear and maintain optimal performance.
  • The coolant system runs best with high-quality, silicate-free coolant suitable for aluminum blocks. Improper fluids may cause internal corrosion or overheating.
  • Be aware of the radiator cap pressure rating—using an incorrect cap may result in reduced efficiency or coolant loss through overflow, especially on long, hard rides.
  • If the bike is used in extremely hot or cold climates, check the manufacturer's recommended coolant solution ratios to ensure year-round cooling and freeze protection.

Safe Disposal

  • Used engine coolant is hazardous. Collect all drained fluid in a sealed container and take it to your local recycling center or hazardous waste facility. Do not pour old coolant down the drain or onto the ground.

With these steps, your 2021 Husqvarna FX350 will retain its cooling efficiency and be ready for whatever challenges you throw at it. MotoSport has the parts and supplies you need for every maintenance job—ride smart, ride prepared.

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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.