How to Change the Coolant on a 2000 KTM 300EXC: Step-by-Step Guide

Shop parts for a 2000 KTM 300EXC Dirt Bike.

Maintaining your 2000 KTM 300EXC ensures optimum performance on the trail – and a proper coolant change is a key part of your maintenance routine. Here is a unique MotoSport guide tailored to your specific year, make, and model.

What Makes the 2000 KTM 300EXC Cooling System Unique?

  • The 300EXC's dual radiators operate in parallel, meaning both must be fully drained and bled for complete coolant replacement.
  • This generation KTM uses an aluminum engine & cooling system, so only use coolant compatible with aluminum components to avoid corrosion.
  • The total coolant capacity is approximately 1.2 liters (1.3 quarts).

What You'll Need

  • 1.2 liters of high-quality coolant safe for aluminum engines
  • Clean funnel and drain pan
  • Basic hand tools (typically an 8 mm or 10 mm socket)
  • Torque wrench (recommended but not required)
  • Shop rags
  • Optional: New drain bolt seal ring

Step 1: Preparation

  • Ensure the engine is completely cool before starting.
  • Place your dirt bike securely on a stand or level surface.
  • Remove the seat and the radiator shrouds for easy access to the radiators and radiator cap if necessary.

Step 2: Draining the Old Coolant

  • Locate the coolant drain bolt on the water pump cover (usually on the lower right side of the engine).
  • Place a drain pan underneath, then remove the drain bolt. Allow all coolant to drain fully.
  • Remove the radiator cap to vent the system and allow faster draining.
  • Optional: To ensure a thorough drain, gently tilt the bike from side to side or remove the lower radiator hose.

Step 3: Inspect & Reassemble

  • Inspect the drain bolt and its seal ring. Replace the ring if damaged or excessively worn.
  • Reinstall the drain bolt. Tighten securely (use your owner's manual for torque specs or tighten snugly if a wrench is unavailable).

Step 4: Filling with New Coolant

  • With the bike upright and level, pour fresh coolant slowly into the radiator via the filler neck. Fill until you reach the base of the filler neck, typically 1.2 liters in total.
  • To minimize air pockets, briefly tilt or gently rock the bike side-to-side while filling.
  • Your KTM 300EXC features a parallel radiator design: ensure both radiators are filled and no trapped air remains.

Step 5: Bleeding the Cooling System

  • To effectively bleed air, slightly jack up the front of the bike (use a ramp or blocks) so the radiators' tops are above the tops of the cylinder head.
    This assists in allowing any trapped air to escape.
  • Add coolant until you see it at the base of the filler neck with no visible bubbles rising.
  • If a bleed screw is present on the cylinder head (common on this model), loosen it briefly – when coolant flows steadily without bubbles, retighten.

Step 6: Recheck & Top Off

  • With the radiator cap still off, start the engine and let it idle for a few seconds. Watch for additional air bubbles. Shut off the engine, check and top off coolant again as needed.
  • Install the radiator cap securely.
  • Reinstall seat and shrouds.

Step 7: Final Checks

  • After your first ride, let the engine cool fully and recheck the coolant level, topping up if necessary.
  • If you experience rapid coolant loss or overheating, recheck for leaks or trapped air, especially around hose clamps and bleed points.

Additional Tips for 2000 KTM 300EXC Owners

  • Always use a pre-mixed, high-quality coolant formulated for dirt bikes and safe for aluminum. Avoid mixing red and green coolants, as they may be chemically incompatible.
  • Routinely inspect radiator fins and cap – a damaged cap may cause boil-over or improper pressure regulation.
  • Flush and fill the system every 1–2 years, especially if the bike is raced or ridden in extreme conditions.
  • Never substitute water only in place of proper coolant, as it lacks anti-corrosion and anti-freeze properties.

Keeping your KTM's cooling system fresh ensures legendary 2-stroke power and reliability wherever your passion takes you. For any replacement parts, gaskets, or upgrade options, MotoSport has you covered.

Related Shopping Categories

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Shop Radiator Hoses for a 2000 KTM 300EXC 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.