How to Change the Coolant in a 2023 Yamaha YZ85 Big Wheel (YZ85LW)

Shop parts for a 2023 Yamaha YZ85LW Dirt Bike.

Keeping the cooling system in your 2023 Yamaha YZ85 Big Wheel (YZ85LW) in top shape is crucial not only for performance but also for engine longevity. The following guide, unique to MotoSport.com, has everything you need to know about changing the coolant and a few extra points for YZ85LW owners.

What Makes the 2023 YZ85LW Unique?

  • The YZ85LW is Yamaha s Big Wheel version, offering larger wheels for improved stability and handling over rough terrain–great for taller riders and racing youth.
  • As a high-performance 2-stroke race machine, keeping the cooling system free of debris and operating at correct temperatures helps prevent overheating and maximizes engine life.

How Often Should You Change the Coolant?

Always check the coolant level before every ride. Yamaha recommends changing the coolant at regular service intervals as indicated in your owner s manual or whenever the coolant appears dirty or contaminated. Change the coolant more often if you ride in muddy or wet conditions, as debris may accelerate wear and contamination.

Tools & Materials You ll Need

  • Drain pan
  • Socket wrench set
  • Funnel
  • Fresh coolant (Yamaha approved or high-quality ethylene glycol-based premix)
  • Clean water (distilled or filtered is best for rinsing)
  • Shop rags
  • Gloves

Step-by-Step Guide: Changing the Coolant

  1. Let Your Bike Cool Down
    Ensure the engine is completely cool before you begin—opening the radiator cap on a hot engine can cause injury.1
  2. Position the Bike
    Place the bike on a stand or level surface. This ensures proper coolant drain and prevents spills.3
  3. Remove the Radiator Cap
    Slowly loosen the radiator cap to relieve pressure.3 Never attempt this when the engine is warm.
  4. Locate & Remove the Drain Bolt
    Find the coolant drain bolt, usually at the bottom of the water pump cover or at the lowest point of the cooling system. Place a drain pan underneath.
    Remove the drain bolt and allow all coolant to drain completely.1
  5. Flush the System (Optional)
    For a thorough service, flush the cooling system with clean, filtered or distilled water. Pour water into the radiator, reinstall the drain bolt temporarily, then drain again until liquid runs clear.
  6. Reinstall the Drain Bolt
    Clean the drain bolt and its sealing washer. Tighten the drain bolt securely, avoiding overtightening.1
  7. Add New Coolant
    Using a funnel, slowly pour new coolant into the radiator until the fluid level reaches the bottom of the radiator filler neck as indicated in your manual.1
    Pause periodically while filling to allow any trapped air to escape.
  8. Bleed Air from the System
    Gently tilt or rock the bike to help release air bubbles. Some owners prefer to start the engine for a few seconds with the cap off, then top up coolant as needed with the engine off.
  9. Reinstall the Radiator Cap
    Securely install the cap once you are confident the air has bled out and fluid is at the proper level.
  10. Check for Leaks & Final Level
    After running the bike to operating temperature, let it cool and recheck the coolant level. Add more if necessary to maintain it at the bottom of the filler neck.4

YZ85LW Coolant Care Tips

  • Only use water for flushing—never for riding without coolant.
  • Never use ordinary tap water for mixing with coolant–minerals can corrode components.
  • Check radiator fins for debris (mud, grass) and clean as needed to avoid overheating.

Disposal

Used coolant is toxic. Dispose of it according to your local regulations–do not pour it down drains or on the ground.

Conclusion

Regularly changing the coolant keeps your 2023 Yamaha YZ85LW running cool and strong, giving you peace of mind on tough trails or at the track. Shop the best parts and accessories at MotoSport to make every ride the best it can be.

Related Shopping Categories

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Shop Tools for a 2023 Yamaha YZ85LW Dirt Bike.

Shop Radiator Hoses for a 2023 Yamaha YZ85LW 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.