How to Change the Coolant in a 2009 Kawasaki KX100

Shop parts for a 2009 Kawasaki KX100 Dirt Bike.

Maintaining your 2009 Kawasaki KX100's cooling system is crucial for engine performance, longevity, and safety. Dirt bikes like the KX100 are known for aggressive riding, making regular coolant changes a must. Below is a MotoSport exclusive guide detailing exactly how to change the coolant, plus model-specific tips every KX100 owner should know.

What You Need

  • High-quality motorcycle coolant (do not use automotive-specific coolants)
  • 10mm socket or box wrench (for drain bolt)
  • Philips screwdriver (for radiator bleeder screw, if equipped)
  • Small funnel
  • Drain pan
  • Clean rags
  • Protective gloves (recommended)

Step-by-Step Instructions

  1. Prepare the Bike – Safety First
    Ensure the bike is on a level stand and the engine is completely cool. Never open the radiator cap on a hot engine; escaping steam can cause severe burns. Wipe loose dirt from around the radiator cap and hoses to prevent contamination.
  2. Remove the Radiator Cap
    Slowly unscrew the radiator cap to release any residual pressure in the system.
  3. Locate & Remove the Drain Bolt
    On the KX100, the coolant drain bolt is found on the lower right side of the cylinder – identifiable by its washer. Place your drain pan beneath this bolt. Remove the bolt with your 10mm tool and allow coolant to fully drain into the pan. Slightly tilting the bike towards the right can help ensure all coolant exits the system.
  4. Open the Radiator Bleeder Screw (if equipped)
    Some KX100 models feature a small bleeder screw on the radiator. Crack it open with a Phillips screwdriver to allow airflow and more thorough draining. This step helps prevent vacuum lock when refilling.
  5. Inspect the Old Coolant
    Examine drained fluid for debris or discoloration—signs of possible corrosion or internal issues. Address any concerns before refilling.
  6. Reinstall Drain Bolt & Tighten
    Clean the bolt and its washer. Hand-thread it back, then torque snugly to factory spec. Do not overtighten, as stripping the threads can cause leaks or expensive repairs.
  7. Add Fresh Coolant
    Using a small funnel, pour new coolant into the radiator until it reaches the base of the filler neck. Use only coolants labeled safe for aluminum radiators.
  8. Bleed the System
    If equipped, close the bleeder screw once coolant seeps from it. With the cap off, lean the bike from side to side or gently bounce the front forks to work out trapped air bubbles. Top off as needed.
  9. Replace the Radiator Cap
    Secure the cap firmly.
  10. Check for Leaks
    Start the bike and let it idle for several minutes, watching closely for leaks. As the engine warms, any further air pockets can work their way out, so recheck coolant level once the engine is cool again.

KX100-Specific Tips & Notes

  • The KX100 cooling system is sensitive to debris; always check radiator fins and exterior for mud or damage after rides–a blocked radiator can quickly cause overheating.
  • For best results, change coolant every 40–50 hours of riding, or at least annually, as recommended for intense motocross use.
  • Never substitute water alone for coolant; the KX100's aluminum head is susceptible to corrosion.
  • If you ride in freezing conditions, confirm your coolant provides adequate anti-freeze protection – not all coolants are designed for cold weather.

By freshening your 2009 KX100's coolant, you ensure peak heat transfer and reduce the risk of costly engine or gasket failure. MotoSport offers a full selection of OEM and performance cooling parts, radiators, and tools to make this maintenance quick and easy.

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Shop Radiator Hoses for a 2009 Kawasaki KX100 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.