How to Change the Coolant in a 1990 Honda CR125
Shop parts for a 1990 Honda CR125 Dirt Bike.
Maintaining proper coolant levels is crucial for the performance and longevity of your 1990 Honda CR125. Changing the coolant not only prevents overheating and corrosion but also ensures smooth rides whether you're ripping berms or tackling gnarly trails. Here's your exclusive MotoSport.com guide for changing the coolant on your CR125, complete with unique insights for owners of this legendary 2-stroke machine.
What Makes the 1990 Honda CR125 Unique?
The 1990 CR125 stands out for its lightweight chassis and high-RPM power delivery – both of which generate considerable heat. Proper cooling is essential, as those narrow radiator cores and high-revving engines can be hard on the system if neglected. Owners should note that factory radiators are particularly sensitive to blockages or low fluid & can be easily damaged if allowed to run dry.
Tools & Materials Needed
- Fresh premixed motorcycle coolant (avoid automotive types)
- Distilled water (if flushing)
- Catch pan or drain pan
- 8mm & 10mm socket or wrench
- Flathead screwdriver (for hose clamps if necessary)
- Clean rags
- Siphon or turkey baster (optional, for overflow)
- Protective gloves
Step-by-Step: Coolant Change Procedure
- Cool the Engine: Always let your CR125 engine cool completely before opening the radiator cap. Hot coolant can cause severe burns.
- Access the Radiator: Remove the radiator shrouds and seat for easier access. In most cases, an 8mm socket is all that's needed.
- Remove the Radiator Cap: Twist the cap off slowly to relieve any pressure.
- Drain the System: Locate the coolant drain bolt on the lower part of the water pump cover (right side of the crankcase, under the radiator hose). Place a drain pan underneath.
Back out the drain bolt with a 10mm socket and let the old coolant flow out completely. Remove the bolt on the bottom of each radiator if equipped for a more thorough drain. - Flush (Optional but Recommended): If coolant appears dirty/rusty, reinstall the drain bolt and fill the radiator with distilled water. Run the engine (cap off) for 2–3 minutes, shut off, let cool, and repeat the drain process. You may repeat this step until water runs out clear.
- Reinstall Drain Bolt: Replace the washer if damaged, then torque the drain bolt snugly (do not overtighten).
- Add New Coolant: Pour fresh premixed coolant into the radiator, filling slowly to prevent air entrapment. Squeeze hoses by hand to help release bubbles.
- Start & Bleed: With the radiator cap off, start the bike and let it idle for a few minutes. Watch for large air bubbles to escape. As fluid settles, top off to just below the neck.
- Seal & Inspect: Reinstall the cap securely. Wipe up any spilled fluid and double-check all fasteners and hose clamps.
- Check Levels: After a short ride, let the bike cool completely and recheck coolant level. Top off if needed – small fluctuations are normal as air purges out.
Important Tips for CR125 Owners
- Never substitute water straight from the tap – always use premixed motorcycle coolant or distilled water mixes to reduce mineral deposits and corrosion.
- Inspect hoses for cracks or leaks during the change. Replace any worn components promptly.
- Avoid overfilling as expansion during operation will force excess coolant into the overflow, potentially creating a mess or depleting your system.
- Check for any coolant leaks at the water pump – 1990 CR125 models are known to develop seal fatigue over time.
- Change your coolant every 1–2 years or every 40–50 riding hours for optimal engine and radiator performance.
Routine coolant changes are one of the easiest, most effective ways to keep your classic CR125 running cool on today's tracks. Treat your bike right – minor maintenance now means more laps and fewer headaches later.
Related Shopping Categories
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Shop Radiator Hoses for a 1990 Honda CR125 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.