How to Change the Coolant in a 2020 Kawasaki KLX300

Shop parts for a 2020 Kawasaki KLX300 Dirt Bike.

Maintaining your 2020 Kawasaki KLX300 includes regular coolant changes to ensure optimal engine temperature and reliability on the trails. While the basics of a coolant flush are similar across dirt bikes, the KLX300 has specific features and access points you'll want to know before you get started.

Tools & Supplies Needed

  • 10mm socket with ratchet
  • 8mm socket (for side panel/fender)
  • Phillips screwdriver
  • Funnel (recommended, but optional)
  • Clean rags
  • Drain pan/container
  • Fresh coolant designed for dirt bikes (look for silicate-free, premixed formula)
  • Distilled (not tap) water if flushing system

Step-by-Step Coolant Change Guide

  1. Preparation:
    • Work with a completely cold engine to avoid burns.
    • Secure the bike upright on a stand.
  2. Remove the Side Panel & Fender:
    • Use the 8mm socket to remove the left side panel, revealing the coolant overflow reservoir – this is specific to the KLX300 layout.
    • Front right fender removal (if needed) can provide easier radiator cap access.
  3. Drain the Coolant:
    • Locate the coolant drain bolt at the bottom of the water pump cover (right side of the engine).
    • Place the drain pan beneath and remove the bolt using the 10mm socket.
    • Slowly remove the radiator cap (right radiator, under the plastic shroud) to allow air in and fluid to drain completely.
    • Open the overflow reservoir cap and drain excess fluid from the tank.
  4. Flush the System (Optional):
    • If switching coolant types or after debris/overheating, pour distilled water into the radiator and allow it to drain.
    • Do not use tap water — minerals can cause corrosion or deposits.
  5. Replace the Drain Bolt:
    • Inspect the drain bolt sealing washer and replace if necessary for leak-free reassembly.
    • Reinstall the drain bolt and tighten it securely but do not overtighten.
  6. Refill with New Coolant:
    • Using a funnel, slowly pour new coolant into the radiator until full.
    • Fill the overflow reservoir to the indicated line (usually the "Full" or "Max" mark).
  7. Bleed the System:
    • Some KLX300 models feature a radiator bleeder screw; open it until fluid flows steadily, then close it.
    • If there is no bleeder, gently rock the bike side to side and squeeze the radiator hoses to purge air pockets.
  8. Reinstall Components:
    • Replace the radiator cap.
    • Reattach the side panel and fender using original hardware.
  9. Warm Up & Inspect:
    • Start the engine and let it idle with the radiator cap on for a few minutes.
    • Shut off, let it cool, and check coolant level again. Top up if needed.
    • Inspect for any leaks at the drain bolt, radiator, or hoses.

KLX300 Owner Tips & Notes

  • The KLX300 uses a liquid-cooled, DOHC engine – overheating can cause serious damage. Stick to the factory coolant interval or replace more frequently if you ride in mud, sand, or hot conditions.
  • Only use silicate-free coolant formulated for aluminum radiators to prevent corrosion and maximize cooling performance.
  • After a coolant change, always double check your overflow tank level after your first ride, as air may purge from the system.
  • If you frequent rough terrain, inspect radiator hoses and clamps for wear or damage during coolant changes.

Proper care of your cooling system means smoother rides and longer engine life. Regular coolant checks and timely servicing will keep your 2020 Kawasaki KLX300 running strong – on the trail or the track.

Related Shopping Categories

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Shop Radiator Hoses for a 2020 Kawasaki KLX300 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.