How to Change the Coolant in a 2009 KTM 105XC

Shop parts for a 2009 KTM 105XC Dirt Bike.

Routine coolant changes are critical for the performance and longevity of your 2009 KTM 105XC. This mini motocrosser's high-revving two-stroke engine runs hot, so a well-maintained cooling system ensures it stays at peak power whether you're trail riding or on the race track. Below is a step-by-step guide, unique to MotoSport, for changing the coolant on your KTM 105XC, plus tips specific to this agile, race-bred dirt bike.

What You'll Need

  • Fresh coolant (pre-mixed or a concentrate plus distilled water)
  • Drain pan or container
  • 8mm socket or wrench
  • Funnel (for clean pouring)
  • Torque wrench (recommended)
  • Shop rags
  • Gloves and safety glasses

Step 1: Let the Bike Cool

Allow the engine to cool completely before you begin. Working on a hot motor or opening the radiator cap on a warm system can cause serious burns due to pressurized hot coolant.

Step 2: Remove the Radiator Cap

Take off the seat and left side panel to access the radiator. Slowly remove the radiator cap to relieve any residual pressure.

Step 3: Drain the Old Coolant

  • Locate the coolant drain bolt on the water pump cover, typically on the right side of the engine.
  • Place your drain pan beneath the drain bolt.
  • Use an 8mm socket to remove the bolt and let the coolant flow out completely.
  • Tilt the bike slightly from side to side to help evacuate trapped coolant, especially since the 105XC's compact chassis can retain fluid in tight spots.

Step 4: Inspect and Clean

  • Check the condition of the drain bolt washer; replace if worn for a proper seal.
  • If coolant was discolored, flush the system by reinstalling the drain bolt, refilling with distilled water, running the engine briefly, then draining again.

Step 5: Reinstall the Drain Bolt

Secure the drain bolt back in place. Use a torque wrench if possible to avoid over-tightening, which is particularly important for the KTM's magnesium water pump housing.

Step 6: Add New Coolant

  • Pour fresh coolant into the radiator slowly, filling up to about 10mm above the radiator fins when the engine is cold–an ideal level for the KTM 105XC.
  • Avoid using tap water with concentrated coolants, as minerals could damage the cooling system.

Step 7: Bleed Air from the System

  • With the radiator cap off, start the engine and let it idle for a few minutes. This helps trapped air rise out of the system.
  • Gently rock the bike and lightly blip the throttle a couple of times to help "burp" any bubbles.
  • Top off coolant as needed to maintain the correct level above the radiator fins.

Step 8: Check Coolant Level and Reassemble

  • Once no more bubbles emerge and the coolant is topped off, reinstall the radiator cap.
  • Reattach the plastic side panel and seat.
  • Start the bike and let it reach normal operating temperature, then check for leaks and re-check the coolant level.

Important Tips for Your 105XC

  • The 2009 KTM 105XC is sensitive to overheating due to its high-strung engine. Always ensure cooling fins and radiators are free of mud and debris for optimal airflow.
  • Use a high-quality motorcycle-specific coolant that's compatible with aluminum and magnesium–a must for the KTM cooling system.
  • At high altitudes or in extreme racing conditions, monitor coolant level frequently and inspect for leaks after every couple of rides.

Dispose of Old Coolant Responsibly

Never pour used coolant down the drain or on the ground. Take it to a local recycling center or automotive store for proper disposal.

Changing your coolant at regular intervals helps extract the best performance and life from your KTM 105XC—stay ahead of the game with proper maintenance.

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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.