How to Change the Coolant in a 2012 Honda CRF150R Big Wheel

Shop parts for a 2012 Honda CRF150R Dirt Bike.

The 2012 Honda CRF150R Big Wheel (RB/Expert) is a high-performance youth motocross bike known for its precise handling, lightweight chassis, and competition-grade liquid-cooled engine. Proper coolant maintenance is crucial for ensuring peak cooling efficiency, especially with the compact radiators and high-revving engine unique to this model. Follow these proprietary step-by-step instructions to safely and effectively change your coolant.

Preparation – What You Need

  • Approved motorcycle coolant (“Pro Honda HP Coolant” or an equivalent silicate-free premix designed for aluminum radiators)
  • Phillips screwdriver
  • Metric socket set or wrench
  • Drain pan
  • Shop towels or rags
  • Protective gloves

Step 1: Ensure a Cool Engine

Never change coolant with a hot engine. Allow the motorcycle to cool thoroughly to avoid burns and ensure accurate draining.

Step 2: Remove the Radiator Shrouds

Use a Phillips screwdriver to remove the bolts securing both radiator shrouds for easier access to the radiator cap and drain bolt.

Step 3: Remove the Radiator Cap

Locate the radiator cap on the left-side radiator. Slowly turn the cap counterclockwise to release any residual pressure, then fully remove it. Always remove the cap before draining to prevent a vacuum that would trap coolant inside.

Step 4: Locate & Remove Drain Bolt

The drain bolt is located on the water pump cover (right side of the engine). Place a drain pan underneath. Use a wrench to remove the bolt. As it loosens, coolant will flow out – be prepared for the stream.

Step 5: Drain the Coolant

Allow the engine and radiator to fully drain. Lean the bike slightly to the right if necessary to ensure all coolant exits. Inspect fluid for contamination – brown, rusty, or oily coolant may indicate further service or a water pump seal issue.

Step 6: Reinstall Drain Bolt

Inspect the drain bolt sealing washer (replace if damaged). Reinstall the bolt and snug it to factory spec. Do not overtighten to prevent case damage.

Step 7: Add New Coolant

Slowly fill the radiator with fresh coolant up to the filler neck. Pause periodically to allow air bubbles to escape. For the CRF150R, total cooling system capacity after disassembly is approximately 0.8 US quarts (0.76 liters).

Step 8: Bleed Air from Cooling System

  • With the radiator cap off, slowly kick over or briefly run the engine to circulate coolant and release air.
  • Watch for bubbles rising in the radiator fill neck.
    Top off coolant as the level drops.

Step 9: Check & Attach Cap, Reassemble

Once bubbling stops and coolant is steady at the top, reinstall the radiator cap securely. Reinstall both shrouds.

Step 10: Inspect for Leaks & Final Check

  • Start the engine and let it idle.
  • Check for leaks around the drain bolt and radiator area.
  • After a brief ride, check coolant level again and top off if necessary.

2012 CRF150R Big Wheel Model Tips & Notes

  • The RB/Big Wheel has slightly different suspension and wheel sizes but coolant service is identical to the standard CRF150R.
  • This bike is made for closed-course competition, so regular high-RPM use increases cooling system stress – change coolant more frequently under racing conditions.
  • Always use silicate-free coolant to prevent corrosion of the aluminum radiators and water passages.
  • If you notice recurring coolant loss, milky oil, or overheating issues, inspect the water pump seals and shaft, which are common replacement parts for the CRF150R at this age and usage level.
  • Check for debris or bent fins in the radiators while you have the shrouds removed, and straighten or clean as needed.

Keeping your 2012 Honda CRF150R Big Wheel running at its best is easy with the proper maintenance supplies and factory-correct replacement parts from MotoSport.

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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.