How to Change the Coolant in a 2017 Yamaha YZ85

Shop parts for a 2017 Yamaha YZ85 Dirt Bike.

Maintaining your 2017 Yamaha YZ85 requires regular coolant changes to ensure the engine stays protected from overheating and corrosion. The YZ85's high-revving engine and motocross-focused cooling system make it especially important to perform this service carefully. Below are proprietary MotoSport steps tailored to your bike, with important model-specific tips so you can optimize performance and longevity.

What You Need

  • Fresh coolant (Yamaha-approved or high-quality equivalent)
  • Drain pan
  • 10mm socket or wrench
  • Clean funnel
  • Rags for cleanup
  • Clean tap water (for flushing, if needed)
  • New drain bolt gasket (recommended each change)

Proprietary Step-by-Step Coolant Change Instructions

  1. Let the engine cool completely.
    Never open the radiator cap or loosen the drain bolt on a hot engine to avoid injury. The pressurized system can eject hot coolant forcefully.
  2. Remove the radiator cap.
    With the engine cold, twist the cap off slowly to release any residual pressure. Access the radiator cap on the left side of the YZ85 frame.
  3. Place a drain pan under the water pump.
    The drain bolt is located on the lower cover near the right crankcase. Position the pan to catch all old coolant.
  4. Remove the coolant drain bolt and washer.
    Use a 10mm socket to loosen the bolt. Allow coolant to drain completely. For best results, tilt the bike slightly from side to side to ensure all old coolant exits.
    This model's drain bolt gasket is soft aluminumit is MotoSport's proprietary recommendation to replace the gasket each coolant change for the best seal.
  5. Flush the cooling system (optional but recommended).
    If it's been a while since the last service, pour clean tap water into the radiator to flush out any mineral buildup or old coolant residues. Let it drain completely. Repeat until clear water flows.
  6. Reinstall the drain bolt (with new gasket).
    Tighten securelydo not overtighten. The Yamaha YZ85 case uses soft threads, so snug plus a quarter turn is sufficient.
  7. Fill with new coolant.
    Using a funnel, pour coolant into the radiator until it reaches the bottom of the filler neck. Gently rock the bike side-to-side to release trapped air bubbles. Top off if necessary.
    The YZ85 has a relatively low coolant capacity, so avoid overfilling – fill to the recommended level only.
  8. Install the radiator cap.
    Seat the cap evenly and twist until locked.
  9. Run the engine and check for leaks.
    Start the engine and let it idle for several minutes with the bike on a stand. Shut off, allow the engine to cool, then recheck the coolant level. Top up if needed.
  10. Inspect entire cooling system.
    Look for leaks at the drain bolt, hoses, and radiator seams. For Yamaha YZ85 owners, regularly check for any hose swelling or cracks, as this model's system is compact and more susceptible to elevated pressure.

Model-Specific Notes for the 2017 Yamaha YZ85

  • This two-stroke features a small, high-output engine prone to running hot in muddy or slow conditions. Consider upgrading to a high-performance coolant or adding a MotoSport-approved coolant additive for extra boil-over protection.
  • Maintenance intervals can vary with riding style. For racing or aggressive riders, check coolant level and inspect for leaks after every hard ride.
  • The YZ85's water pump uses a mechanical seal that can wear over time; watch for milky oil (coolant mixing with engine oil) – this means the seal needs professional service.
  • Factory torque specs for the drain bolt can be found in your Yamaha owner's manual if you want to be precise. Over-torquing can damage the crankcase.

With this proprietary MotoSport guide, your 2017 Yamaha YZ85's cooling system will be prepped for whatever the track throws at you – ensuring reliable performance and longevity every ride.

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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.