How to Change the Coolant in a 2006 KTM 250EXC-RFS

Shop parts for a 2006 KTM 250EXC-RFS Dirt Bike.

Regularly changing the coolant in your 2006 KTM 250EXC-RFS is key for performance and engine longevity. The 250EXC-RFS uses a robust liquid-cooled RFS (Racing Four Stroke) engine which relies on clean, high-quality coolant to prevent overheating – especially on challenging trails and technical terrain. Here is MotoSport.com's proprietary step-by-step guide to safely and effectively replace the coolant on this specific dirt bike model.

What You Will Need

  • Crescent wrench or 10mm socket
  • Drain pan
  • Funnel
  • Shop towels or rags
  • Premium motorcycle engine coolant (silicate-free for aluminum engines)
  • Distilled water (if mixing coolant)
  • Safety gloves & eyewear

Changing the Coolant – Step by Step

  1. Prep the bike. Make sure the engine is completely cool. Place the bike on a level stand to avoid accidental spills.
  2. Remove the radiator cap. Gently twist off the radiator cap on the left side of the tank. This relieves system pressure and helps coolant drain efficiently.
  3. Locate the coolant drain bolt. On the 2006 250EXC-RFS, the coolant drain is a 10mm bolt on the water pump cover (right side of engine case). It is usually marked by a copper washer for a positive seal .
  4. Drain the old coolant. Put your drain pan under the water pump. Carefully remove the drain bolt and let the coolant flow out completely. Open the radiator cap if you did not already, for best drainage.
  5. Flush if needed. For older or contaminated coolant, you may add distilled water to the radiator, reinstall the drain bolt, run the engine briefly, then repeat the drain process. Repeat until water runs clear .
  6. Reinstall the drain bolt. Inspect and replace the copper washer if it is damaged, then snug the drain bolt back on (do not overtighten).
  7. Fill with new coolant. Use a funnel to pour the fresh coolant slowly into the radiator until it reaches the opening. Gently tip the bike side-to-side to help release any trapped air.
  8. Bleed air from the system. Start the engine and let it idle with the radiator cap off. As the coolant circulates, bubbles may rise to the top. Top off coolant as needed. Once no more bubbles appear, shut off the engine and securely reinstall the radiator cap.
  9. Check for leaks and ride. Wipe off any spills and inspect for leaks around the water pump and drain bolt. Ride briefly and monitor the coolant level again after the first heat cycle, topping up if required.

Model-Specific Tips for the 2006 KTM 250EXC-RFS

  • Avoid tap water. Always use distilled water when mixing coolant, as minerals in tap water can cause scale and corrosion in the RFS engine’s lightweight alloy components.
  • Stick with silicate-free coolant. Silicate-containing fluids can damage the KTM’s water pump seal and inner passages over time.
  • Check hoses and clamps. The 250EXC-RFS is over fifteen years old – inspect all cooling hoses and clamps for cracks or fatigue, and replace any suspect parts during your coolant service. See the full parts selection above.
  • Coolant change interval. For optimal protection, refresh the coolant every 1–2 years, or every 40–50 hours of ride time .

Why this Service Matters

The KTM 250EXC-RFS’s high-revving four-stroke engine generates substantial heat. Regular coolant changes prevent overheating, preserve seals, and maintain consistent power output for demanding off-road conditions. Neglecting this service can lead to premature engine wear or catastrophic overheating, common concerns with all RFS models run hard or with old coolant.

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.