How to Change the Coolant in a 2010 Husqvarna WR125: Complete Guide

Shop parts for a 2010 Husqvarna WR125 Dirt Bike.

Changing the coolant on your 2010 Husqvarna WR125 is a critical maintenance step that keeps your two-stroke enduro performing reliably, especially during high-revving rides. This step-by-step guide is tailored specifically for the WR125, with practical instructions and exclusive tips for MotoSport customers.

What You Will Need

  • Fresh, premixed motorcycle coolant (do not use tap water–use only premixed, or distilled water with coolant concentrate)
  • 10 mm socket or wrench
  • Drain pan
  • Phillips screwdriver (for bodywork removal, if necessary)
  • Gloves & safety glasses
  • Rags or paper towels

Step 1: Preparation

  • Ensure the WR125 is completely cool and parked on a level surface using a stand to keep it steady.
  • Remove the seat and left side panel for easier access to the radiator (use a Phillips screwdriver).

Step 2: Remove the Radiator Cap

  • Locate the radiator cap at the top of the left radiator.
  • Turn it counter-clockwise and remove it carefully to relieve any residual pressure.

Step 3: Drain the Old Coolant

  • Position the drain pan under the water pump (lower right-side of the engine).
  • The WR125 typically uses the water pump cover bolt as the coolant drain. Use a 10 mm wrench to remove the lowest bolt–coolant will begin to flow out quickly.
  • Allow the system to completely drain. To speed up draining, gently tip the bike side-to-side.

Step 4: Flush the System (Optional but Recommended)

  • For best maintenance, fill the radiator with distilled water after draining, reattach the drain bolt, and run the engine for just 30 seconds.
  • Turn off the bike, remove the drain bolt, and drain the flush water completely.

Step 5: Refit Drain Bolt

  • Inspect the drain bolt and washer for wear or damage; replace if necessary.
  • Reinstall the bolt and tighten securely, but do not overtighten to avoid stripping the threads.

Step 6: Add New Coolant

  • Slowly pour fresh coolant into the radiator until it reaches the top of the filler neck.
  • Fill the overflow reservoir (if equipped) to the specified level.

Step 7: Bleed Air from the System

  • With the radiator cap off, start the engine and let it idle for a few minutes. Gently rock the bike side to side and blip the throttle.
  • This helps trapped air escape. Watch the coolant–it may drop as air is expelled.
  • Top up coolant as needed until the level stabilizes.

Step 8: Finish Up

  • Turn off the engine and let the bike cool, then recheck the coolant level.
  • Reinstall the radiator cap and any removed panels or seat.
  • Wipe up any spills and properly dispose of the old coolant in accordance with local regulations.

WR125 Maintenance Tips

  • The WR125 has a lightweight, simple cooling system; always inspect the radiator and hoses for damage or leaks during coolant servicing.
  • Use only motorcycle-specific coolants free of silicates and phosphates to avoid water pump and seal wear.
  • Check the overflow reservoir regularly, especially after your first ride post-change.
  • If you frequently ride in muddy or rocky conditions, inspect your radiator guards for debris–a clogged radiator will cause overheating.

Why Regular Coolant Changes Matter

  • Old coolant loses its anti-corrosion properties and can cause internal scaling or overheating.
  • Hard riding and racing conditions mean the WR125 coolant breaks down faster than in casual use–change it every year or after heavy use.
  • Consistent coolant maintenance will extend the life of your water pump, seals, and engine internals–keeping your Husky roaring down the trail.

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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.