How to Change the Coolant in a 2013 Yamaha YZ250

Shop parts for a 2013 Yamaha YZ250 Dirt Bike.

Changing the coolant in your 2013 Yamaha YZ250 is a vital maintenance task that keeps your two-stroke running cool under tough riding conditions. The YZ250 is renowned for its light weight, aggressive power delivery, and simplicity of maintenance, so performing a coolant change is refreshingly straightforward. Below, MotoSport guides you through a step-by-step process specific to your MMY model – with a few YZ250-specific notes to ensure great results.

What You Need

  • Coolant (Yamaha-recommended or quality aftermarket)
  • Distilled water (for flushing)
  • Catching pan or bucket
  • 8mm socket or wrench
  • Rags for cleanup

Step 1: Prep Your Workspace

  • Let the engine cool completely before working on the cooling system – pressure and hot fluid can cause injury.
  • Place your YZ250 on a stand so it's level and secure. Position a drain pan underneath the bike, below the water pump on the right side of the engine.

Step 2: Drain Old Coolant

  • Remove the radiator cap to allow air in – this helps the coolant drain freely.
  • Locate the 8mm coolant drain bolt on the lower water pump cover (right side of the engine case).
  • Loosen and remove this bolt; coolant will start draining. Let it pour into the pan until flow stops entirely.
  • Inspect the old coolant for debris or oil contamination, which could indicate a seal failure – a not uncommon concern on older YZ250s.

Step 3: Flush the System (Recommended)

  • Reinstall the drain bolt loosely. Fill the radiator with distilled water (not tap water – minerals can deposit and damage the cooling system).
  • Replace the radiator cap, start the engine, and let it idle for 1-2 minutes just to circulate the water. Do not overheat.
  • Shut off, allow to cool for a minute, then repeat the drain process. You can flush once or twice until the water runs clear.

Step 4: Fill With Fresh Coolant

  • Ensure the drain bolt is torque-snugged (but don't overtighten – stripped threads may occur on YZ250 water pump covers if over-torqued).
  • Pour your new pre-mixed coolant (recommended coolant amount is approximately 1.0 liter for the YZ250) slowly into the radiator until just below the filler neck.
  • With the cap off, gently tilt and shake the bike from side to side to dislodge trapped air bubbles.
  • Top off as needed, then reinstall the radiator cap.

Step 5: Check for Leaks & Final Inspection

  • Start the engine and let it idle for several minutes. As it warms, inspect around the drain bolt, water pump, and radiator for leaks.
  • Once cooled, re-check coolant level by removing the radiator cap and top off if necessary.

2013 YZ250-Specific Notes

  • The YZ250's cooling system is robust, but the water pump cover drain bolt threads can be vulnerable to stripping, so always use moderate torque and fresh crush washers.
  • If your bike develops coolant loss through the weep hole under the water pump, this often signals a worn water pump seal – these are easily serviced and worth addressing while draining coolant.
  • When re-filling, avoid mixing coolant types – flush thoroughly if switching brands or coolant base (like moving from conventional to silicate-free racing coolant).
  • Periodically inspect radiator fins for mud or bends, which can reduce cooling efficiency, especially after muddy rides or tip-overs common in MX or woods racing.

Final Thoughts

The YZ250 is a favorite for its low maintenance demands, and keeping the cooling system fresh is one of the easiest ways to protect your motor for seasons to come. Plan on performing a coolant change at least once per year or more often for frequent racers and hard riders.

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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.