How to Change the Coolant in a 2019 Honda CRF125FB
Shop parts for a 2019 Honda CRF125FB Dirt Bike.
Your 2019 Honda CRF125FB dirt bike is engineered for reliability, but regular cooling system maintenance is vital to prolong its life and keep it running strong. Coolant breaks down over time, reducing its protective qualities, so Honda recommends a coolant change every two years or as needed based on riding conditions. The CRF125FB uses a compact, race-derived cooling system – special care is required to keep it efficient and safe.
What Makes the 2019 CRF125FB Unique?
- Compact radiator design positioned on the left side for maximum protection and airflow.
- No radiator fan – relies on motion and airflow, making maintenance and coolant quality even more critical, especially for low-speed or trail riding conditions.
- Low overall fluid capacity – mistakes in refilling or air-pocket issues can cause overheating faster than on larger bikes.
What You'll Need
- Fresh, pre-mixed 50/50 silicate-free motorcycle coolant (avoid car coolants, and never use plain water except for flushing)
- Metric socket set and ratchet
- 5mm Allen wrench
- Phillips head screwdriver
- Drain pan
- Clean funnel
- Paper towels and gloves
Step-by-Step Coolant Change Guide
- Ensure the engine is cold. Never open the radiator cap on a hot engine – severe burns and coolant spray can result.
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Remove the left side cover.
- Use the 5mm Allen and remove the bolts identified as bolts A and B, and the collar.
- Carefully pull the cover away, freeing the prong from the grommet and the locating boss from its hole. Set aside the cover.
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Access the radiator and drain bolt.
- The radiator cap is under the left side shroud. Use the screwdriver to remove any retaining screws, then twist the cap off carefully.
- The coolant drain bolt is typically found at the base of the water pump cover by the right footpeg. Place your drain pan beneath.
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Drain the old coolant.
- Remove the drain bolt slowly – the used coolant will flow out. Remove the radiator cap fully to speed draining.
- Allow all fluid to exit the system. Check for sediment or discoloration; these may signal the need for system flushing (ask a pro for advice if you suspect buildup).
- Inspect and replace the drain bolt washer if necessary. A worn washer can cause leaks. Replace with a new crush washer if the old one is damaged.
- Reinstall the drain bolt. Tighten it firmly but do not overtighten – you can strip the threads or crack the cover.
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Add new coolant.
- Insert a funnel and slowly pour in new coolant until the radiator is filled just below the neck.
- Gently rock the bike side to side and squeeze the radiator hoses to help eliminate air bubbles.
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Bleed air and re-check levels.
- With the radiator cap off, start the engine and let it idle for a minute or two. Watch for any coolant movement indicating trapped air escaping.
- Shut off the engine, top up coolant as needed.
- Replace the radiator cap and reinstall the side cover. Double check all fasteners are secure. Hook the tab, align the prong with the grommet, and install both bolts as described above.
- Properly dispose of the old coolant. Never pour it down the drain or into the soil. Collect for recycling or take to a hazardous waste facility.
Important Tips for CRF125FB Owners
- Use only Honda-approved or equivalent coolant – the aluminum parts in your CRF's engine and radiator are susceptible to corrosion from improper formulas.
- After the first ride post-service, re-check the level and look for leaks.
- Never overfill the radiator or reservoir – expansion will force out excess, making a mess and potentially causing overheating.
- If your bike overheats easily in slow trails, consider taking extra care with coolant changes and ensure no air pockets remain in the system.
Regular coolant changes are essential to maintain performance and avoid costly repairs on your 2019 Honda CRF125FB. Keep your ride cool, and always follow basic safety during maintenance.
Related Shopping Categories
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Shop Radiator Hoses for a 2019 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.