How to Change the Coolant in a 2017 KTM 250SX

Shop parts for a 2017 KTM 250SX Dirt Bike.

Performing regular coolant changes on your 2017 KTM 250SX is essential to maintain optimal engine temperature and performance, especially during demanding rides. Follow this step-by-step MotoSport guide for a smooth, mess-free process and take note of model-specific tips to keep your two-stroke running strong.

What You Need

  • New coolant recommended for dirt bikes (silicate-free for aluminum radiators is best)
  • 8mm socket or wrench (for drain bolt)
  • Drain pan or suitable container
  • Funnel
  • Clean rags
  • Protective gloves and safety glasses

Step 1: Preparation

  • Ensure the engine is completely cool before starting. Opening the system hot can cause scalding injuries.
  • Stand the motorcycle upright on a stable stand to help coolant drain fully.

Step 2: Remove the Radiator Cap

  • Locate the radiator cap on the left side of the bike, just above the shroud.
  • Twist the cap counterclockwise to remove it, releasing any pressure in the system.

Step 3: Drain the Coolant

  • Place your drain pan directly below the water pump cover (right side of the engine).
  • Identify the drain bolt — it's an 8mm bolt with a copper washer located on the lowest part of the water pump cover.
  • Remove the drain bolt and allow all coolant to flow out. This may take a few minutes – tip the bike gently side to side for a complete drain.
  • Inspect the coolant for debris or oil, which can signal engine issues that may require further inspection.

Step 4: Reinstall the Drain Bolt

  • When coolant has finished draining, clean the bolt and sealing surface with a rag.
  • Reinstall the drain bolt with the copper washer. Tighten securely, but do not overtighten. If you have a torque wrench, refer to your manual for the exact torque setting.

Step 5: Add New Coolant

  • Insert a funnel into the radiator opening and slowly pour in new coolant.
  • Fill until the fluid is just below the bottom of the radiator neck.

Step 6: Bleed Air From the System

  • Squeeze the upper and lower radiator hoses a few times to help trapped air escape.
  • Top up the coolant if the level drops after removing air bubbles.

Step 7: Reinstall the Radiator Cap

  • Ensure the fill level is correct, then reinstall the radiator cap securely.

Step 8: Run the Engine & Recheck

  • Start the engine and let it idle for several minutes with the bike upright. Watch the temperature if your KTM is equipped with a digital or bar-style gauge.
  • Turn off the engine, allow it to cool, then check coolant level once more. Add fluid if needed.

Special Notes for 2017 KTM 250SX Owners

  • The 2017 KTM 250SX uses an aluminum radiator – avoid coolant types containing silicates or borates, as they can accelerate corrosion.
  • Inspect the condition of radiator hoses and T-pipes; the plastic components and hose clamps can age or loosen over time .
  • If you notice air bubbles or loss of coolant after a ride, check for leaks around the water pump and T-pipe connections .
  • The two-stroke 250SX cooling system is compact by design. Overheating can occur quicker than on four-strokes if coolant is low or air remains trapped in the system.

Changing your coolant is not only routine maintenance – it's essential for reliable performance. Plan to inspect your coolant every 30 hours of ride time, or as indicated in your KTM service schedule, and always use quality parts and fluids for best results.

Related Shopping Categories

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Shop Temperature Sensors for a 2017 KTM 250SX Dirt Bike.

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Shop Radiator Hoses for a 2017 KTM 250SX Dirt Bike.

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.