How to Change the Coolant in a 2023 Honda CRF125FB

Shop parts for a 2023 Honda CRF125FB Dirt Bike.

Maintaining proper coolant levels in your 2023 Honda CRF125FB is crucial for optimal engine performance and longevity. A regular coolant change protects against overheating, corrosion, and freezing, which are especially important when pushing your MMY dirt bike on aggressive trails or track days. Below, MotoSport provides a step-by-step proprietary guide tailored specifically for the CRF125FB owner.

Required Tools & Supplies

  • Silicate-free, ready-to-use motorcycle coolant or premix
  • Drain pan
  • 8mm and 10mm sockets & ratchet
  • Phillips head screwdriver
  • Shop rags or paper towels
  • Funnel (optional, but recommended)
  • Replacement crush washer for drain bolt (recommended)
  • Gloves and eye protection

Coolant Change Procedure

  1. Preparation:
    • Ensure the engine is completely cool before beginning to avoid injury from hot coolant or pressurized steam.
    • Park your CRF125FB on a level, stable surface with the bike upright.
  2. Accessing the Radiator Cap & Drain Bolt:
    • Remove the radiator shroud or side panel as needed for radiator access–typically held on with 8mm bolts. Consult your owner's manual for the location of the panels for your specific year and configuration.
    • Position your drain pan beneath the engine drain bolt. The drain bolt is usually found at the lowest point of the water pump cover.
  3. Draining Old Coolant:
    • Loosen the radiator cap slowly to relieve any residual pressure, then remove it fully.
    • Remove the coolant drain bolt and crush washer, allowing the coolant to flow into the drain pan. Inspect the old coolant–cloudiness, debris, or rust can indicate internal wear or contamination in your bike's cooling system.
    • After draining, install a new crush washer on the drain bolt and torque it to spec according to your owner's manual.
  4. Flushing (Optional but Recommended):
    • If your coolant appears dirty, you may now flush the system with distilled water. Repeat the drain process until water runs clear, then fully drain.
  5. Refilling the System:
    • Using your funnel, pour fresh premix coolant into the radiator until it reaches the neck. The CRF125FB typically holds just under a quart during a standard change–check your owner's manual for precise capacity.
  6. Bleeding Air from the Cooling System:
    • Leave the radiator cap off and start the engine. Allow it to idle for a minute, gently rocking the bike to help bubbles escape. Watch for air pockets escaping and top up as necessary.
    • Once bubbling stops and coolant holds steady at the neck, shut off the engine and top off if needed.
    • Install the radiator cap securely to prevent leaks and overheating.
  7. Reassembly & Inspection:
    • Reinstall any shrouds or side panels previously removed.
    • Wipe away spills and run the bike until the engine reaches normal temperature. Recheck coolant level after cooling down–top off the reservoir if needed.
    • Check under the bike for leaks at the drain bolt and hose connections.

Things to Know About the 2023 CRF125FB

  • Coolant Loss: Honda notes a small amount of coolant loss (approx. 20-60 cm3) via the overflow tube is normal. Excessive loss requires inspection for leaks or failing radiator cap.
  • Use Only Silicate-Free Coolant: The Honda CRF lineup, including the CRF125FB, requires silicate-free coolant to prevent corrosion and deposit formation in the compact, high-efficiency radiators.
  • Service Interval: For aggressive riding or racing, replace coolant yearly. For typical trail use, every two years or per manual recommendations is sufficient.
  • Unique to the CRF125FB: This MMY features a compact radiator assembly with relatively low coolant capacity–overfilling can lead to expansion and excess discharge from the overflow, while underfilling causes overheating. Always ensure correct fill level and system bleed.

Final Tips from MotoSport

  • Use only clean, uncontaminated coolant for filling and bleeding.
  • Always inspect the radiator cap and hoses during each coolant change–replace them if you see signs of wear, swelling, or cracking.
  • Proper coolant disposal is vital. Take used coolant to a local recycling center or hazardous waste facility–never pour into drains or soil.

Investing a short amount of time in coolant maintenance will keep your 2023 Honda CRF125FB running safe, cool, and powerful on every ride. If you need OEM or performance cooling system parts, MotoSport has you covered.

Related Shopping Categories

Shop Radiators for a 2023 Honda CRF125FB Dirt Bike.

Shop Coolant for a 2023 Honda CRF125FB Dirt Bike.

Shop Temperature Sensors for a 2023 Honda CRF125FB Dirt Bike.

Shop Tools for a 2023 Honda CRF125FB Dirt Bike.

Shop Radiator Hoses for a 2023 Honda CRF125FB 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.