How to Change the Coolant in a 2018 Honda CRF150R Big Wheel

Shop parts for a 2018 Honda CRF150R Dirt Bike.

Keeping your 2018 Honda CRF150R Big Wheel (RB) running strong means regular maintenance–and that includes coolant changes. This guide will walk you through a safe and effective coolant replacement, while calling out details unique to the CRF150RB.

What Makes the 2018 CRF150RB Unique?

  • The Big Wheel (RB) version has a higher ground clearance and larger-diameter wheels, but the engine and cooling system are functionally identical to the standard CRF150R.
  • Honda's recommended coolant is Pro Honda HP Coolant, and the specified coolant capacity is 0.80 US qt (0.76 L) after system disassembly. Expect similar capacity for a basic drain and refill.
  • This model is tuned for competition use–never run the engine without coolant as it can quickly overheat.

Tools & Supplies Needed

  • Fresh coolant (Pro Honda HP Coolant or equivalent, silicate-free and aluminum-safe)
  • Drain pan
  • 8mm socket or wrench (for drain bolt)
  • Phillips screwdriver (for radiator shrouds, if needed)
  • Clean rags
  • Funnel
  • Gloves

Step–by–Step Coolant Change Procedure

  1. Make sure the engine is cool. A hot system can release pressurized coolant–wait at least an hour after riding.
  2. Position the bike upright on a stable stand to ensure proper draining.
  3. Remove the radiator cap. The CRF150RB's cap is on top of the left radiator. Loosen–do not force–to release any remaining pressure. This step ensures the coolant drains completely.
  4. Locate the water pump drain bolt (bottom right side of the engine case). Place a drain pan underneath. Remove the bolt (it has a copper washer for sealing). Let the coolant drain fully. When the flow slows, you can gently rock the bike side to side to help evacuate trapped coolant.
  5. Inspect the removed coolant. If it's especially dirty or rusty, you might want to flush the system with distilled water–just fill, run briefly, and drain again before final refill.
  6. Reinstall the drain bolt with its copper washer. Tighten securely, but do not overtighten to avoid stripping the threads.
  7. Refill the cooling system. Pour new coolant into the radiator using a funnel. Pour slowly to avoid air pockets. Fill to just below the neck.
  8. Bleed air from system. Rock the bike gently, and squeeze radiator hoses with your hand to help move trapped air. Add more coolant if the level drops.
  9. Reinstall radiator cap securely.
  10. Start the engine and let it idle for 3-5 minutes. With the bike upright, watch the temperature and monitor for leaks. After shutting off and allowing it to cool, check coolant level again and top off if necessary.

Additional CRF150RB Owner Tips

  • Always use silicate-free coolant designed for modern aluminum engines–conventional green automotive coolants can corrode the CRF's components over time.
  • Change coolant at least once per year if you race, or every two years for casual riding. More frequent changes benefit bikes ridden in harsh conditions.
  • Inspect radiator hoses, clamps, and the radiator cap for cracks or wear when changing coolant–replace any damaged parts promptly.
  • The CRF150RB is designed for closed-course competition use only and is not legal for street riding.

By keeping up with regular coolant changes and using the right formula, you protect your 2018 Honda CRF150R Big Wheel's high-performance engine from overheating and corrosion. If you need any replacement hoses, caps, or radiators, MotoSport has you covered for genuine parts and accessories.

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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.