How to Change the Coolant in a 2008 Husqvarna WR125

Shop parts for a 2008 Husqvarna WR125 Dirt Bike.

Keeping your 2008 Husqvarna WR125’s cooling system maintained is crucial to ensure reliable performance and to prevent overheating – especially under aggressive and off-road riding conditions. Changing the coolant is a straightforward process, but the WR125 has a few model-specific details you should keep in mind.

What Makes the 2008 WR125 Unique?

  • The WR125 is a high-revving two-stroke, so consistent cooling is critical for piston and cylinder health.
  • This model’s radiator and coolant routing design mean air pockets can form if the system is not bled properly.
  • The magnesium engine cases are sensitive to corrosion, so only use high-quality, silicate-free motorcycle coolant.

Tools & Supplies You’ll Need

  • Socket set or wrench (10 mm works for most fasteners on the coolant system)
  • Drain pan
  • New silicate-free coolant, pre-mixed or distilled water plus concentrate
  • Clean rags
  • Safety gloves

Step-by-Step Coolant Change

  1. Ensure the Engine is Cool: Never open the radiator cap when hot—let the bike cool completely to vent any pressure safely.
  2. Remove Protective Panels: Take off the seat and, if necessary, the right side panel to access the radiator and overflow bottle.
  3. Open Radiator Cap: With the bike upright, slowly unscrew the radiator cap to release any residual pressure.
  4. Locate and Remove the Drain Bolt: The drain bolt is usually found at the bottom of the water pump or low point on the engine case, below the right side of the bike. Place your drain pan underneath and remove the bolt. Allow all old coolant to drain.
    Optionally, disconnect the lower radiator hose if you want a more thorough flush.
  5. Flush (Optional): For best results, you can add distilled water, re-install the drain bolt, run the engine briefly, and drain again to remove any remaining old coolant.
  6. Reinstall Drain Bolt: Replace the washer if worn. Torque the bolt to spec to avoid stripping soft cases.
  7. Add New Coolant: Slowly fill the radiator with your chosen coolant until it reaches the base of the filler neck.
  8. Bleed the System: Leave the radiator cap off, start the bike, and let it idle for a few minutes. Gently rock the bike and rev the engine a few times to help release trapped air bubbles. Top up as needed. Repeat this until the coolant level stabilizes.
  9. Top Off Overflow Tank: Fill the overflow reservoir to the recommended line to ensure proper expansion space.
  10. Reassemble and Inspect: Replace the radiator cap, reinstall all panels and the seat, and check for leaks. After riding and once cooled, recheck both levels to verify no air remains.

Final Tips for WR125 Owners

  • Dispose of used coolant responsibly–never dump it on the ground. Most auto parts stores accept it for recycling.
  • Inspect hoses and clamps during the process–these are common leak points on older dirt bikes.
  • Check coolant level regularly after the first few rides, as air can sometimes work free, especially after hard use.

Regular coolant changes extend the life of your WR125’s engine, especially given Husqvarna’s high-performance design. If you notice frequent overheating or coolant loss, inspect your water pump seal and impeller for wear–common wear items on this model.

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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.