How to Change the Coolant in a 1989 Kawasaki KX125: Step-by-Step Guide
Shop parts for a 1989 Kawasaki KX125 Dirt Bike.
Routine coolant changes are essential to keep your 1989 Kawasaki KX125 running cool and performing at its best, especially given the demands of off-road riding. Below is MotoSport's detailed, proprietary guide for a thorough coolant change tailored specifically for your KX125.
Tools & Supplies Needed
- 10mm socket or wrench
- Large Phillips screwdriver
- Rag for clean-up
- Fresh coolant (preferably motocross-specific)
- Container to catch old coolant
- Funnel (optional, but helpful)
KX125-Specific Tips
- Main Bleeder Screw: Your 1989 KX125 features a radiator bleeder screw, making draining and bleeding the system efficient—use it to prevent vacuum lock and ensure a full refill.
- Inspect the Cap: The radiator cap's seal is critical. If it's worn or doesn't seal firmly, replace it to maintain correct pressure and prevent overheating on this high-revving, air-cooled two-stroke engine.
- Check Hoses & Clamps: Vintage hoses may become brittle or leak; inspect and replace if cracking or swelling is found.
Step-by-Step Coolant Change Instructions
- Ensure the Bike is Cool: Allow your KX125 to cool completely before servicing to avoid injury from hot coolant and pressurized systems.
- Remove the Seat & Side Panels: Access to the radiator and fill area may require removing bodywork, especially for a clean pour and inspection.
- Remove the Radiator Cap: Unscrew the cap slowly to release any residual pressure. Opening the cap allows the system to vent and improves flow while draining.
- Locate and Remove the Drain Bolt: Find the coolant drain bolt, typically located at the bottom of the water pump housing on the right side of the engine. Use the 10mm socket to carefully remove it, holding your catch container beneath to collect the old coolant.
- Open the Bleeder Screw: Use the Phillips screwdriver to open the radiator's bleeder screw on the opposite side. This step helps the coolant drain completely without forming a vacuum in the system.
- Drain Completely: Tilt the bike gently if necessary to remove trapped coolant from both radiators. Allow coolant to fully drain before proceeding.
- Inspect the Coolant: Check the drained fluid for debris, corrosion, or oil—signs you may need further cooling system service.
- Reinstall Drain Bolt & Bleeder Screw: Thread both in by hand to avoid cross-threading, then tighten to a snug fit. Do not overtighten, as stripping these components is possible on an older bike.
- Refill with Fresh Coolant: Using a funnel, pour in new coolant up to the fill neck. Allow it to settle and check for leaks. If air bubbles appear, briefly open the bleeder screw while the cap is still off to release trapped air, then tighten securely.
- Reinstall Radiator Cap: Inspect the cap, and if it's in good condition, reinstall it with a firm push and twist until you feel resistance and it locks in place.
- Start and Warm Up: Start the engine and let it idle for a few minutes. Watch the coolant level in the radiator, and check for leaks around the pump, hoses, and drain bolt. If needed, shut off the engine, cool, and top off the coolant.
- Cleanup: Wipe down any spills, reinstall plastics, and responsibly dispose of your old coolant.
Important Notes for 1989 KX125 Owners
- This model is prized for its lightweight two-stroke engine—perfect cooling is crucial for optimal power and longevity.
- Inspect radiator fins for bends or debris each time you service the system. Damaged fins reduce efficiency and can cause overheating on demanding rides.
- The cooling capacity is relatively small, so use high-quality, compatible coolant and check fluid levels often, especially in hot weather or hard riding.
- If your bike is original, consider replacing aged seals, hoses, and the radiator cap for improved reliability.
Related Shopping Categories
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Shop Radiator Hoses for a 1989 Kawasaki KX125 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.