How to Change the Coolant in a 2019 KAWASAKI KX100

Shop parts for a 2019 KAWASAKI KX100 Dirt Bike.

Maintaining the correct coolant level and quality in your 2019 Kawasaki KX100 is crucial for long-term engine performance and reliability. Regular coolant changes help prevent overheating, corrosion, and premature wear, especially under the demands of motocross and trail riding. The KX100 uses a liquid-cooled two-stroke engine, where the cooling system is vital due to high-rev operation and the compact design of this model.

What You Will Need

  • Fresh, motorcycle-approved coolant (consider Engine Ice or a glycol-based coolant)
  • 10mm socket or wrench
  • Phillips screwdriver
  • Drip pan or suitable container
  • Rags for cleanup
  • Funnel
  • Optional: Compressed air if switching coolant types

Step-by-Step Coolant Change Guide

  1. Preparation
    Ensure the bike is completely cool before you start. Position it upright on a stand and remove the seat and shrouds if they block access to the radiator.
  2. Remove the Radiator Cap
    Gently unscrew the radiator cap. On the KX100, always remove the cap first to release internal pressure and prevent coolant from spraying out when the drain bolt is removed.
    Certain Kawasaki models, including the KX100, have a radiator bleeder screw on the opposite radiator–use a Phillips screwdriver to open it to allow air to enter and the coolant to drain smoothly.
    Tip: This step helps prevent vacuum lock and ensures a complete drain.
  3. Drain the Old Coolant
    Locate the coolant drain bolt on the water pump—it is typically a 10mm bolt near the bottom right side of the engine. Place your drip pan under the bolt and loosen it. Allow all coolant to drain out.
    To help all fluid evacuate, gently tilt the bike toward the drain. Replace the drain bolt and tighten to manufacturer specifications once done.
  4. Optional: Flush If Changing Coolant Type
    If you are switching from a water-based to a different type of coolant, consider flushing the system. Remove both radiator hoses and use compressed air to blow out any residual old coolant before reassembly.
  5. Add New Coolant
    Use a funnel to slowly add new coolant via the radiator cap opening until full. For the 2019 KX100, fill both left and right radiators evenly.
    If your model has a bleeder screw, leave it open while filling until coolant flows out, then tighten it. This helps purge any trapped air for efficient cooling.
  6. Bleed and Check System
    With the radiator cap off, gently rock the bike side-to-side to help dislodge any air bubbles. Check coolant level and top off as needed. Replace the radiator cap.
  7. Inspect and Clean
    Double-check for leaks around the drain bolt and radiator cap. Wipe any spilled coolant, return plastics and seat if removed.
  8. Run and Re-Check
    Start the engine and let it idle for a couple of minutes, then shut it down and allow cooling. Re-check coolant level and top off if necessary.

Things to Know About the 2019 KX100 Cooling System

  • The KX100's high-revving, liquid-cooled two-stroke engine is particularly sensitive to overheating, so regular coolant replacement is even more critical than on some other models.
  • Use only motorcycle-specific coolant—never use plain water or automotive antifreeze, as these can damage internal gaskets, seals, and the water pump.
  • The owner's manual recommends checking coolant every ride and changing it approximately every 40–50 engine hours or at least once per riding season for best performance.
  • Debris between the radiator fins is common in motocross–inspect and clean fins regularly to ensure airflow.
  • Always handle used coolant responsibly—dispose according to local regulations.

Final Thoughts

Keeping your KX100's cooling system in top shape will deliver peak power, prevent expensive repairs, and extend your bike's life. Change your coolant routinely and inspect your cooling system before each ride for lasting peace of mind on the track or 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.