How to Change the Coolant in a 1989 Kawasaki KX250
Shop parts for a 1989 Kawasaki KX250 Dirt Bike.
Changing the coolant in your 1989 Kawasaki KX250 is one of the most important routine maintenance tasks to keep your engine running at the right temperature and avoid long-term damage. The KX250 is a proven two-stroke powerhouse with a reputation for robust performance, but like any liquid-cooled engine, it relies on clean, fresh coolant to protect internals from overheating and corrosion. Below, we walk you through the proprietary MotoSport step-by-step process tailored specifically for this iconic dirt bike, along with essential model-specific tips.
Tools and Supplies Needed
- New motorcycle coolant (silicate-free and suitable for aluminum components)
- Socket set (10mm and 8mm sockets recommended)
- Phillips screwdriver
- Drain pan or container
- Clean rags
- Gloves and safety glasses
Step-by-Step Coolant Replacement for the 1989 KX250
- Preparation: Ensure your engine is completely cool before starting. Place the bike on a stable stand and remove the radiator shrouds for full access to the top of the radiators.
- Access and Remove Radiator Cap: Remove the radiator cap slowly to relieve any pressure.
- Locate and Remove the Drain Bolt: On the right side of the engine, locate the coolant drain bolt at the bottom of the water pump cover. Place a drain pan beneath, then remove the bolt (usually 8mm). Allow all coolant to drain. On this era of KX250, you may also have a bleeder screw on one of the radiator tanks–open it with a small screwdriver to help the coolant flow freely and avoid vacuum lock during draining and refilling.
- Inspect Components: While the system is empty, inspect hoses for wear, radiator fins for damage or debris, and caps for a tight seal. Deformed fins can be gently straightened with a thin screwdriver–this helps maximize airflow and efficiency.
- Reinstall Drain Bolt and Close Bleeder: Once drained, reinstall the drain bolt by hand first to avoid cross-threading, then tighten securely. Close the bleeder screw if opened.
- Refill with Coolant: Slowly fill the radiator with fresh, high-quality coolant recommended for off-road two-stroke engines and safe for aluminum. Leave the radiator cap off for now.
- Bleed the System: Slightly tilt the bike side-to-side and gently squeeze radiator hoses to help any air escape. Open the bleeder screw again briefly if necessary, until coolant drips steadily without large air bubbles.
- Top Off and Secure Cap: Fill all the way to the top, reinstall the cap, and make sure it clicks past the safety catch.
- Warm Up and Recheck: Start the engine and let it idle to operating temperature. Shut it down, let it cool, and recheck coolant level – top off if needed. Inspect for leaks.
1989 KX250-Specific Notes
- The aluminum radiators are tough but prone to dings and twisted mounting flanges if the bike has seen a fall. Carefully straighten any bends, as misalignment can cause plastic shroud fitment issues and reduce cooling efficiency.
- The KX250 water pump impeller is robust, but when replacing seals or performing a deep service, always use high-temperature grease on the shaft to avoid premature seal wear.
- Always use a coolant designed for off-road aluminum systems to prevent internal corrosion common in older KX models.
Coolant Maintenance Tips
- Change the coolant at least once per season for best protection.
- Flush the system with distilled water if old coolant is heavily discolored or contaminated.
- Inspect the radiator cap for spring tension–a weak cap can cause boiling and loss of coolant during hard motos.
Your 1989 Kawasaki KX250 is a classic performer that will keep running strong with the right care. Proper cooling system maintenance is one of the best ways to protect your engine—and keep those legendary motos alive.
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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.