How to Change the Coolant in a 2017 Yamaha YZ450FX: MotoSport.com Official Guide

Shop parts for a 2017 Yamaha YZ450FX Dirt Bike.

Proper cooling is essential for the high performance and longevity of your 2017 Yamaha YZ450FX. Follow this MotoSport-exclusive, step-by-step guide to keep your dirt bike running at peak power and protect your engine during demanding rides.

What You'll Need

  • Fresh coolant (Yamaha-approved or performance aftermarket type for aluminum radiators)
  • Drain pan
  • Socket wrench set
  • Screwdrivers
  • Rags and gloves

Before You Start: Model-Specific Notes

  • The 2017 YZ450FX features a unique cross-country tuned cooling system compared to the motocross YZ450F, with a radiator designed for low-speed airflow and heavy clutch use. Always use a coolant formulated for high-performance off-road applications to avoid boiling over.
  • The radiator cap sits higher on this model for easier filling, and its shroud offers quick access. The system holds approximately 1.15 quarts (1.1 liters) of coolant out of the factorymatch or slightly exceed this with new coolant for best results.

Step 1: Let the Engine Cool

  • Coolant can be dangerously hot and pressurized. Always allow the bike to cool completely before beginning service. Opening the radiator cap on a hot bike risks serious burns from steam and fluid spray.

Step 2: Remove the Skid Plate & Shrouds (If Necessary)

  • For easy access to the drain bolt and radiator cap, remove the right-side radiator shroud and, if installed, any skid plate or guards.

Step 3: Drain the Old Coolant

  • Place your drain pan directly under the water pump area (on the lower right side of the engine).
  • Locate and remove the coolant drain boltusually a 8mm or 10mm bolt on the lower side of the water pump housing.
  • Remove the radiator cap at the same time to let air in and help the old coolant drain out quickly. Tip the bike slightly toward the drain side if needed.
  • If the coolant is dirty or contaminated, flush the system with distilled water: reinstall the drain bolt, fill system with water, run engine for 1 minute, then drain again.

Step 4: Inspect & Replace Components As Needed

  • Check hoses and clamps for cracks, leaks, or signs of drying out—replace as you order new coolant if needed.
  • Inspect your radiator cap gasket; a worn seal here can cause premature boiling or loss of coolant.

Step 5: Reinstall the Drain Bolt

  • Wipe the drain bolt clean and reinstall securely. Use a new washer on the drain bolt if yours is worn to prevent leaks.

Step 6: Fill with Fresh Coolant

  • Slowly pour your new coolant into the radiator filler neck until it reaches the bottom of the filler neck (visible and just below the cap seat).
  • Gently rock the bike side to side or squeeze the lower radiator hose a few times to help purge trapped air in the system.
  • Refit the radiator cap securely.

Step 7: Bleed the System & Check for Leaks

  • Start the engine and let it idle with the radiator cap on. Watch the temperature for a few minutes and check beneath the bike for leaks.
  • Shut off the engine, let cool, and remove the cap again to top off the coolant if the level dropped after air escaped.
  • Reinstall shrouds, guards, and skid plate once everything is leak-free and secured.

Owner Tip: Service Intervals & Best Practices

  • Yamaha recommends changing coolant every two years or after heavy use. For aggressive off-road riding or races, check coolant color and level after each event.
  • The YZ450FX's close-ratio gearbox and wide-ratio application mean the engine spends long periods under load–keep an eye on your radiator fins for debris (mud and grass) and clean after muddy rides.
  • Never mix different coolant types unless both are labeled compatible. For extreme climates, consider performance coolants with higher boiling points for peace of mind.

With proper maintenance, your YZ450FX will handle any trail or enduro course you throw at it. Keep your cooling system fresh for maximum reliability on 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.