How to Change the Coolant in a 2009 Husqvarna WR125

Shop parts for a 2009 Husqvarna WR125 Dirt Bike.

Routine coolant changes are crucial for maintaining optimal engine temperature and protecting vital components on your 2009 Husqvarna WR125. This process helps prevent overheating, corrosion, and ensures peak performanceespecially important with the WR125's high-revving two-stroke engine and its proven race-ready cooling system. Follow this exclusive MotoSport.com guide for a safe, thorough coolant flush and refill.

Before You Start

  • Allow the engine to cool completely–hot coolant can cause serious burns.
  • Prepare new coolant (silicate-free, designed for aluminum engines), a catch pan, socket set, and a funnel.
  • Consider using distilled water for flushing if you need to do a complete system clean.

Step-by-Step Coolant Change for the 2009 Husqvarna WR125

  • Remove the radiator cap: Locate and unscrew the left-side radiator cap to release pressure in the cooling system.
  • Drain the old coolant: Position a suitable catch pan beneath the right side of the engineunder the coolant drain screw (usually at the lower end of the water pump cover). Loosen and remove the drain screw and allow the coolant to drain fully. Open the radiator cap completely after loosening the drain screw to improve flow.
  • Flush, if needed: If the coolant is dirty, replace the drain screw briefly and fill the radiator with distilled water. Run the engine for one to two minutes with the cap off. Turn off, let cool, and repeat draining to remove any residue.
  • Reinstall drain screw: After draining, securely reinstall the drain screw. Tighten to manufacturer torque specs (over-tightening can strip aluminum threads).
  • Pour in fresh coolant: Use a funnel to fill the radiator up to the base of the filler neck. If your model also features an overflow reservoir, fill it to the recommended mark, usually visible on the tank. Most coolants are pre-mixed, but always check if your coolant requires dilution (typically 50/50 with distilled water).
  • Burp the system: Start the WR125 and gently rock the bike side-to-side with the cap off, allowing air bubbles to escape as coolant circulates. Add more coolant if the level drops. Continue until no more air emerges and the coolant level remains steady.
  • Re-check and secure: Replace the radiator cap, ensuring it is secure. Start and idle the bike until it's warm–monitor for leaks and double-check the coolant level in the radiator and reservoir after the engine cools down again. Top off if needed.
  • Dispose of old coolant responsibly: Take used coolant to a recycling center or automotive storenever pour it down drains.

Tips Unique to the 2009 Husqvarna WR125

  • This model features a narrow two-stroke engine that can run hot, especially under load. Fresh coolant helps prevent vapor lock and prolongs the life of gaskets and the water pump.
  • Regularly inspect hoses and radiator fins for damage or debris—clogged fins reduce cooling efficiency.
  • OEM coolant meeting Husqvarna's aluminum-safe specifications is recommended to avoid corrosion inside the engine and radiators.
  • If you perform frequent deep water crossings, consider changing coolant more often to protect against moisture intrusion.

Your WR125 is designed for demanding off-road conditions. Regular coolant service is a simple way to ensure maximum reliability and performance every ride.

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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.