How to Change the Coolant in a 1990 Honda CR250

Shop parts for a 1990 Honda CR250 Dirt Bike.

Keeping your 1990 Honda CR250 in peak condition requires periodic coolant changes. Coolant not only regulates engine temperature but also prevents corrosion and internal buildup that can shorten the lifespan of your dirt bike. The steps below provide a proprietary MotoSport.com guide for safely and efficiently changing the coolant on this classic two-stroke machine, with tips specific to the 1990 CR250.

Preparation – What You Need

  • New coolant (Honda-recommended or high-quality motorcycle coolant)
  • Distilled water (optional for flushing but recommended for a complete system clean)
  • Drain pan
  • 10 mm wrench or socket
  • Screwdriver (for radiator shrouds and panels)
  • Shop rags
  • Gloves and eye protection

Step 1: Access the Radiator System

  • Place your bike on a level stand and allow the engine to cool completely.
  • Remove the seat, side panels, and radiator shrouds to fully access the radiators. On the 1990 CR250, plastics and the fuel tank are easily removed for excellent access to the radiator cap and hoses, making this job less tedious than on many modern bikes.

Step 2: Drain the Old Coolant

  • Place the drain pan beneath the water pump area on the right engine case.
  • Locate and remove the radiator cap slowly to relieve system pressure.
  • Locate the water pump drain bolt (typically at the lowest point of the water pump cover) and remove it using a 10 mm wrench or socket.
  • Allow all coolant to drain. You can also gently tip the bike from side to side for complete drainage.
  • Inspect the sealing washer on the drain bolt and replace if damaged—CR250s from this era are known for soft washers, so replacement is wise to avoid leaks.

Step 3: (Optional) Flush the Cooling System

  • For a full flush, reinstall the drain bolt, fill the system with distilled water, and start the engine briefly to circulate (do not overheat).
  • Turn off and allow to cool, then drain again completely.

Step 4: Refill with Coolant

  • Reinstall and tighten the drain bolt gently–over-tightening is a common mistake and can strip the aluminum threads.
  • Pour new coolant slowly into the radiator. Stop once coolant reaches just below the filler neck.
  • Tilt the bike side to side to release air bubbles. Squeeze hoses to help air escape.
  • Fill the coolant overflow tank to the indicated level, if equipped.

Step 5: Bleed Air & Check Levels

  • Start the engine and let it idle with the radiator cap off (monitor temperature closely).
  • Watch for escaping air bubbles; add more coolant if level drops.
  • Once air bubbles stop and the bike reaches operating temperature, shut down the engine and let it cool fully. Check and top off the coolant as necessary—CR250s often need a second top-off after the first heat cycle due to trapped air in the system.
  • Reinstall the radiator cap securely.

Things to Know About the 1990 CR250

  • The cooling system on this model is renowned for reliability but relies on unobstructed radiator flow. Inspect your radiators for bent fins or mud, and clean as necessary.
  • Early CR250 radiators and hoses are robust, but gaskets and clamps become brittle with age–inspect carefully and consider preemptive replacement using parts from MotoSport.com.
  • The two-stroke engine on your 1990 CR250 generates more heat at high RPM, making clean and effective coolant vital for optimal performance and longevity.
  • If you notice repeated coolant loss or overheating, inspect water pump seals and impeller–these are known wear points on this generation.

Final Checks

  • Always use motorcycle-specific or Honda-approved coolant to protect internal aluminum components.
  • Dispose of old coolant responsibly–never dump down drains or onto the ground.
  • Replace the seat, side panels, shrouds, and fuel tank securely.

Your classic 1990 Honda CR250 is now ready for another season of reliable and cool riding. Performing regular coolant changes is one of the easiest ways to ensure longevity and peak performance from your vintage race legend.

Related Shopping Categories

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Shop Tools for a 1990 Honda CR250 Dirt Bike.

Shop Radiator Hoses for a 1990 Honda CR250 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.