How to Change the Coolant in a 2015 Honda CRF125F: Step-by-Step Guide

Shop parts for a 2015 Honda CRF125F Dirt Bike.

Changing the coolant on your 2015 Honda CRF125F is a vital part of regular maintenance that ensures your dirt bike runs cool and reliably, especially when you're pushing it on the trails. The following proprietary guide is tailored for MotoSport customers seeking the correct process and expert insights for the CRF125F model.

Why Change Your Coolant?

  • Fresh coolant maintains optimal operating temperatures and prevents overheating.
  • Old coolant can lead to corrosion, scale, and premature component wear.
  • Changing coolant every two years or after about 40–50 hours of run time is optimal for most dirt bikes; always check your owner’s manual for specifics related to your riding habits.

Items You’ll Need

  • Fresh 50/50 pre-mixed, silicate-free radiator coolant formulated for motorcycles
  • Drain pan
  • Ratchet with extension, 8mm or 10mm socket
  • Phillips head screwdriver
  • Funnel
  • Shop towels or rags
  • New crush washer for drain bolt (recommended but not required each time)

Step 1: Preparation & Safety

  • Allow the engine to cool completely before beginning—never open the radiator cap while the engine is hot.
  • Position the bike on a stable, level surface and secure it on a stand.

Step 2: Remove Bodywork for Access

  • Remove the left side cover by taking out Bolt A and Bolt B using the appropriate socket, then gently release the prong from the rubber grommet and the boss from the shroud hole.
  • For easy access to the radiator and drain bolt, you may also need to remove the seat by uninstalling mounting bolts, depending on your setup.

Step 3: Drain Old Coolant

  • Place your drain pan beneath the water pump area (lower right side of the engine).
  • Slowly remove the radiator cap to relieve any pressure in the system.
  • Locate the coolant drain bolt (usually located on the water pump housing). Remove it with the correct socket; coolant will start to flow out.
  • Inspect the crush washer on the drain bolt and replace if damaged.
  • Once draining slows, you can lean the bike gently side to side to ensure all fluid exits.

Step 4: Reinstall Drain Bolt

  • Clean the bolt and threads before reinstalling with a new crush washer if you have one.
  • Tighten to specified torque (see your owner’s manual if needed).

Step 5: Refill with New Coolant

  • Using a funnel, pour new coolant into the radiator slowly, allowing air to escape and preventing spills.
  • Fill until the coolant reaches the base of the radiator filler neck.

Step 6: Bleed Air & Top Off

  • With the radiator cap still off, start the engine and let it idle for a few minutes. This helps the new coolant circulate and air bubbles escape.
  • Shut off the bike, let it cool for a moment, and check the coolant level again. Top off as needed.
  • Securely reinstall the radiator cap.

Step 7: Reinstall Bodywork

  • Install the side cover and seat in reverse order, ensuring all tabs, bolts, and connectors are properly secured.

CRF125F Model-Specific Notes

  • The CRF125F uses a straightforward single-radiator system with easy-access plastics, making coolant changes relatively simple for most owners.
  • This model’s cooling system is sized for its trail-oriented engine but can be sensitive to coolant quality and correct fill levels. Always use manufacturer-recommended fluids for best results.
  • After any coolant change, monitor your bike for the first ride—check for leaks at the drain bolt and radiator cap and re-top if necessary.
  • If your bike frequently overheats or loses coolant, inspect for hose cracks, radiator cap issues, or possible leaks at the water pump area.

Expert Tips from MotoSport

  • Dispose of old coolant in accordance with local regulations, as it is toxic to pets and the environment.
  • If your CRF125F is new or has just undergone major service, recheck coolant level after the first ride.
  • Always store your bike with the correct coolant mix to prevent freeze or boil events if riding year-round.

Related Shopping Categories

Shop Radiators for a 2015 Honda CRF125F Dirt Bike.

Shop Coolant for a 2015 Honda CRF125F Dirt Bike.

Shop Temperature Sensors for a 2015 Honda CRF125F Dirt Bike.

Shop Tools for a 2015 Honda CRF125F Dirt Bike.

Shop Radiator Hoses for a 2015 Honda CRF125F 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.