How to Change the Coolant in a 2021 KAWASAKI KX85: A Step-by-Step Guide

Shop parts for a 2021 KAWASAKI KX85 Dirt Bike.

Keeping your 2021 Kawasaki KX85 running cool under pressure starts with maintaining the cooling system. Changing the coolant not only wards off overheating but also extends engine life by preventing corrosion and maintaining peak performance. Here’s how to change the coolant in your KX85, along with important notes about this model every owner should know.

What You Need

  • Fresh motorcycle-specific coolant (avoid generic or car coolants)
  • 10mm socket or wrench
  • Phillips screwdriver
  • Drain pan
  • Funnel
  • Clean rags for spills and cleanup

Preparation – Cool Engine Always

Only service the cooling system when the engine is completely cool; removing the radiator cap from a hot engine can cause severe burns due to pressure release.

Step 1: Locate and Remove the Radiator Cap

On the KX85, remove the radiator cap with a rag, slowly twisting to the first stop to let any residual pressure escape. The cap is located at the top of the left radiator. Set the cap aside.

Step 2: Open Bleeder Screw (If Equipped)

Some Kawasaki models, including the KX85, feature a bleeder screw on the right-side radiator. Loosen this screw with a Phillips screwdriver. This allows the system to breathe and prevents a vacuum lock, ensuring a smooth drain and refill. Removing both the cap and bleeder first also reduces messy, high-pressure coolant bursts when you remove the drain bolt.

Step 3: Locate and Remove the Drain Bolt

The drain bolt is typically a 10mm bolt at the bottom of the water pump, found on the lower right side of the engine. Carefully loosen and remove it, allowing old coolant to drain completely into your pan. Tip the bike gently toward the drain side to ensure full evacuation.

Step 4: Inspect Components

  • Check the condition of the drain bolt washer; replace if worn or damaged.
  • Inspect the radiator cap for deteriorating seals or warping.
  • Examine coolant color – cloudy or rusty fluid can indicate contamination or corrosion inside the cooling system.

Step 5: Reinstall Drain Bolt & Tighten

Reinstall the drain bolt securely (do not overtighten) to avoid stripping. Ensure the washer seats flat – leaks often happen here if not properly aligned.

Step 6: Add Fresh Coolant

  • Use a funnel to carefully pour new coolant into the left radiator’s fill opening.
  • Continue filling until coolant appears at the bleeder screw or is visible in the left radiator just below the neck.

Step 7: Bleed Air From the System

Tighten the bleeder screw as soon as coolant flows from it, confirming air is purged. Gently rock the bike or squeeze the radiator hoses to encourage any trapped air to escape during filling. Top off as needed.

Step 8: Finalize – Cap and Clean

  • Reinstall and tighten the radiator cap.
  • Wipe away any spilled coolant.
  • Allow the engine to idle with the cap on for several minutes, then shut off and check coolant level again after cooling. Top off if necessary.

Tips & Notes for 2021 KX85 Owners

  • Change coolant every 12 months or sooner under extreme conditions.
  • The KX85 uses an aluminum cooling system – only use aluminum-safe, premixed motorcycle coolant to prevent galvanic corrosion.
  • Monitor for leaks after refill, especially around all service points.
  • If switching between different coolant types (e.g., from water-based to non-water-based), flush the system thoroughly to avoid cross-contamination and deposits.

Maintaining your KX85’s cooling system is crucial for reliability and long-term performance. These steps will ensure your ride stays cool & fast, lap after lap.

Related Shopping Categories

Shop Radiators for a 2021 KAWASAKI KX85 Dirt Bike.

Shop Coolant for a 2021 KAWASAKI KX85 Dirt Bike.

Shop Temperature Sensors for a 2021 KAWASAKI KX85 Dirt Bike.

Shop Tools for a 2021 KAWASAKI KX85 Dirt Bike.

Shop Radiator Hoses for a 2021 KAWASAKI KX85 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.