How to Change the Coolant in a 2021 Honda CRF150R Big Wheel

Shop parts for a 2021 Honda CRF150R Dirt Bike.

Regular coolant changes are essential to keep your 2021 Honda CRF150R Big Wheel running strong whether you're racing or trail riding. This modeloften called the CRF150RBfeatures a high-revving, liquid-cooled engine that depends on proper cooling for peak performance and long life. Here's how MotoSport recommends changing the coolant, along with a few CRF150RB-specific tips every owner should know.

What You'll Need

  • Pro Honda HP Coolant (or comparable high-performance motorcycle coolant)
  • Socket wrench set
  • Drain pan
  • Funnel
  • Clean rags
  • Protective gloves

Steps to Change the Coolant

  1. Preparation
    Ensure the engine is cool. Place your bike securely on a stand. Remove the radiator shrouds if needed for better access.
  2. Access the Radiator Cap
    Locate the radiator cap on the left side of the bike. Slowly twist off the cap to release any pressure and set it aside.
  3. Drain the Old Coolant
    Identify the coolant drain bolt on the water pump, which is mounted low on the right side of the engine case. Place a drain pan beneath it. Using a socket wrench, remove the drain bolt and washer. Allow coolant to fully drain. To speed up the process, tip the bike lightly side to side. Remove the radiator cap completely if you haven't already, to help coolant flow out faster.
    Tip: Dispose of old coolant properly–it's toxic to pets and the environment.
  4. Inspect Seals and Hoses
    Take a moment to check hoses, clamps, and the drain bolt's copper washer. Replace any parts that look cracked or worn, as leaks can cause overheating.
  5. Reinstall the Drain Bolt
    Clean the bolt and washer thoroughly, then thread them back in by hand before tightening with your wrench. Do not overtighten–a snug fit is sufficient for the copper washer to seal.
  6. Add New Coolant
    Using a funnel, slowly pour new coolant into the radiator until it reaches the base of the filler neck. The system capacity (after disassembly) is about 0.76 liters (0.80 US qt). Avoid overfilling.
  7. Remove Air Pockets
    With the cap off, tip the bike gently from side to side and squeeze the radiator hoses to help release trapped air.
    Start the engine and let it idle for a minute. Keep an eye on coolant level–add more if it drops, and stop the engine if you see leaks.
  8. Recheck and Top Off
    Shut off the engine and let it cool down. Double-check the coolant level, topping off if necessary. Reinstall the radiator cap.
  9. Test Ride and Inspect
    Take a short ride, then check for any leaks or low levels. If everything looks good, you're ready to ride hard again.

Specific Tips for the 2021 CRF150RB

  • The CRF150RB is competition-focused and does not have a coolant overflow tank. Always check the coolant level directly at the radiator.
  • Use only high-quality, silicate-free coolant designed for aluminum engines. Automotive coolant can damage the system.
  • Replace the coolant at least once a year, or more often if riding in extreme heat or racing conditions.
  • Inspect the water pump area. If you notice coolant leaks at the pump, the mechanical seal or shaft may need service–common on high-rpm models like the 150RB.
  • This bike's tight tolerances mean that overheating can cause serious engine issues. Always inspect for leaks and monitor for unusual temperature spikes after service.

Following this guide will help keep your 2021 Honda CRF150R Big Wheel reliable, letting you focus on your next MotoSport adventure. Remember: maintenance now saves headaches later, so ride prepared.

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Shop Radiator Hoses for a 2021 Honda CRF150R 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.