How to Change the Coolant in a 2006 Yamaha YZ250

Shop parts for a 2006 Yamaha YZ250 Dirt Bike.

The 2006 Yamaha YZ250 is a legendary two-stroke dirt bike, prized for its lightweight chassis and aggressive power delivery. Regular coolant changes are vital for maintaining peak performance and protecting the engine from overheating, especially given this model's aluminum components and intense riding conditions. Here is the definitive MotoSport guide for changing the coolant on your YZ250, tailored specifically for your bike.

What You Need

  • High quality ethylene glycol antifreeze with anti-corrosion properties (designed for aluminum engines)
  • Clean soft water (distilled or deionized recommended)
  • Coolant catch pan
  • 10 mm socket or wrench
  • Funnel
  • Clean rags
  • Protective gloves

YZ250-Specific Notes

  • This model's cooling system capacity is 1.20 L (1.27 US qt).
  • Use a 50% coolant/50% soft water mix for best results and engine longevity.
  • The coolant drain bolt is on the right side of the engine. Always replace the copper washer under the bolt if damaged.
  • Torque the drain bolt to 10 Nm (7.2 ft–lb) after draining and before refilling.2

Step-by-Step Coolant Change Guide

  1. Allow Engine to Completely Cool
    Never open the radiator cap or drain bolt when hot—the system is under pressure and can release boiling coolant.
  2. Remove the Radiator Cap
    Carefully loosen and remove the cap to allow airflow and ensure full drainage.
  3. Drain the Old Coolant
    Place your catch pan under the right side of the engine.
    Locate the coolant drain bolt (typically near the water pump). Use a 10 mm socket to remove the bolt along with the sealing washer.
    Let all coolant flow out. Tip the bike gently side-to-side to clear trapped fluid from the radiators.2
  4. Flush the System (Recommended)
    Reinstall the drain bolt and temporarily fill the system with clean soft water.
    Replace the cap, run the engine for a couple of minutes, then shut off and allow to cool.
    Drain the water as before. This helps clear contaminants and old coolant.3
  5. Reinstall the Drain Bolt
    Ensure the sealing washer is in good condition.
    Torque the drain bolt to 10 Nm (7.2 ft-lb) for a proper seal.
  6. Mix and Add New Coolant
    Mix 50% high-quality coolant with 50% soft water.
    Pour into the radiator using a funnel until coolant reaches the neck of the filler.
    Gently tilt the bike side to side to release trapped air. Top off as needed.2
  7. Bleed the System
    Briefly run the motor with the cap off, allowing any remaining air bubbles to escape.
    Watch for drops in coolant level and top off as necessary.4
  8. Inspect and Replace the Cap
    Ensure the radiator cap gasket is intact.
    Replace the cap and wipe away any excess coolant from the bike and engine.
  9. Check for Leaks
    After a short ride, double-check the coolant level and inspect the drain bolt and hoses for leaks.

Pro Tips for YZ250 Owners

  • Inspect hoses for age cracks—replace as needed to prevent future leaks.
  • Never use pure antifreeze; always dilute 50/50 with soft water. This ensures proper heat transfer and anti-corrosion protection.
  • Flush and replace coolant at least once a year, or more frequently for high-intensity or hot-climate riding.
  • Carry spare premixed coolant when riding remote tracks. Overheating from leaks can be catastrophic for your engine.

Routine coolant service on your YZ250 is a straightforward process that protects your powerplant and maximizes track performance. Stay ahead of maintenance and enjoy every ride knowing your cooling system is race-ready.

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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.