How to Change the Coolant in a 2009 Honda CRF150R Big Wheel

Shop parts for a 2009 Honda CRF150RB Dirt Bike.

Maintaining the cooling system on your 2009 Honda CRF150R Big Wheel is critical for peak performance – especially if you ride hard or compete. Here's a step-by-step guide designed for the CRF150RB, along with important notes unique to this high-revving mini racer.

What You'll Need

  • Pro Honda HP Coolant or another high-quality, silicate-free motorcycle coolant
  • Distilled water for flushing (do not use tap water)
  • Drain pan
  • 8mm or 10mm wrench
  • Funnel
  • Clean rags
  • Protective gloves & safety glasses

Step 1: Preparation

  • Allow the engine to cool completely before starting.
  • Place your bike on a stand for stability.
  • Remove the seat and shrouds for better access if necessary.

Step 2: Draining the Old Coolant

  • Locate the radiator cap on the right side of the bike – remove it slowly to relieve pressure.
  • Find the coolant drain bolt (usually on the water pump cover, right side engine case).
  • Position the drain pan underneath and remove the drain bolt. Let the coolant drain fully from the system.
  • It's recommended to remove the radiator cap before the bolt to allow air in and improve draining.

Step 3: Flushing the System

  • For the CRF150RB, flushing is especially important before adding new coolant. Pour distilled water into the radiator and let it drain by reinstalling and removing the drain bolt a few times.
  • Do not use tap water, as minerals can build up and damage the high-performance system.
  • Blow out excess water with compressed air, or let it drain out completely.

Step 4: Filling with New Coolant

  • Reinstall and torque the drain bolt securely.
  • Using a funnel, pour new coolant slowly into the radiator neck until it's full (cooling system capacity is about 0.76 liters for this model).
  • Lean the bike side-to-side to help move trapped air bubbles out of the system.
  • Crank the engine over (without starting) a few times to help the pump circulate coolant – top off as needed.
  • Reinstall the radiator cap.

Step 5: Check for Leaks & Final Steps

  • Start the engine and let it idle until it's fully warm.
  • Let the bike cool, then recheck coolant level. Top off if necessary.
  • Inspect for leaks especially around the water pump and drain bolt.

CRF150R/RB Model Notes

  • The CRF150RB Big Wheel is designed for competition and high-output riding. Overheating can result in power loss or engine wear – never ignore cooling maintenance.
  • Check your radiator for debris after sandy or muddy rides. Blocked fins are a common cause of overheating in this model.
  • If you notice persistent coolant loss or overheating, inspect the water pump for seal or bearing issues – these are known wear areas on the CRF150RB.

Stay on top of cooling system service – your CRF150RB will reward you with consistent power and reliability on every ride.

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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.