How to change the coolant in a 2018 Kawasaki KX85 Dirt Bike

How to Change the Coolant in a 2018 Kawasaki KX85

Routine coolant changes keep your 2018 Kawasaki KX85 running cooler, prolong engine life, and help maximize performance on the track or trail. With its high-revving, performance-focused engine, the KX85 cooling system works hard and is sensitive to overheating–regular maintenance is key for this model. Before starting, always ensure the engine is completely cold to prevent burns or injury.

What You–ll Need

• Fresh coolant (use one approved for aluminum engines)
• Distilled water (for flushing if needed)
• 10mm socket or wrench
• Phillips screwdriver (for the bleeder screw if equipped)
• Drain pan
• Clean funnel
• Rags for cleanup

Step 1: Remove the Radiator Cap

Firmly push down and twist the radiator cap to remove it. Take care, as any remaining pressure can cause fluid to spurt out. Stay clear of the fill opening while removing the cap.

Step 2: Locate and Remove the Drain Bolt

Find the coolant drain bolt, which is typically located on the lower part of the water pump cover. Place your drain pan underneath, and use your 10mm socket to remove the bolt. Allow the coolant to drain completely. To speed up draining, you may also remove the radiator bleeder screw if present, which can help release trapped fluid and prevent vacuum lock.

Step 3: Flush the System (Optional for Thorough Service)

If you–re swapping coolant types or it's been a long interval, flush the system. With the drain bolt reinstalled, pour distilled water (or a recommended flush mix) into the radiator. Remove the drain bolt to let it flush through. Repeat until water runs clear.

Step 4: Reinstall the Drain Bolt

Wipe off any coolant residue. Thread the drain bolt back in by hand and then tighten gently with your wrench. These bolts are small–do not overtighten and risk stripping threads.

Step 5: Add New Coolant

Insert the funnel in the radiator neck. Slowly pour in your fresh coolant until the radiator is filled to the top. Watch for bubbles; pause if you see gurgling, letting air escape.

Step 6: Bleed the System

Start the engine briefly without the radiator cap. Watch the fluid level, as trapped air may escape. Add more coolant as needed to keep the radiator full during this process. If your KX85 has a bleeder screw on the opposite radiator or head, open it to vent air before tightening securely.

Step 7: Final Level Check & Cap Replacement

Once no more air bubbles rise and the coolant is level at the radiator neck, shut off the engine. Top off if required. Clean off any spills, then replace the radiator cap firmly.

Special Notes for the 2018 KX85 Owner

• KX85 cooling systems are compact, increasing the risk of overheating with low coolant. Always check levels after hard rides or any suspected leaks.
• Use only coolants compatible with aluminum radiators–avoid straight tap water, or you risk corrosion and poor performance.
• This model may accumulate air pockets near the cylinder head, making proper bleeding crucial for reliable cooling.
• Inspect hoses and radiator fins frequently; trail riding or crashes can easily cause damage that leads to overheating.

By following this process, you keep your 2018 KX85–s powerhouse engine cool and ready for every moto.

Related Shopping Categories

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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.