How to Change the Coolant in a 1987 Honda CR250

Shop parts for a 1987 Honda CR250 Dirt Bike.

If you own a 1987 Honda CR250, routine coolant changes are vital for optimal performance and engine longevity. The CR250 uses a liquid-cooled two-stroke engine, and keeping the cooling system clean helps prevent overheating and corrosion. Here is an exclusive MotoSport guide showing you how to flush and refill the coolant on your vintage motocross machine.

What You Will Need

  • 50/50 premixed ethylene glycol coolant (safe for aluminum radiators)
  • Distilled water (for flushing)
  • Drain pan
  • Socket or wrench set (10mm for drain bolt)
  • Pliers or screwdriver (for removing radiator cap and hoses if needed)
  • New washer for drain bolt (recommended)
  • Clean rags
  • Protective gloves

1. Prepare the Bike

  • Ensure the engine is completely cool. Hot coolant under pressure can cause serious burns.
  • Position your CR250 on a stable stand and remove the seat and side number plates for access if necessary. Remove the fuel tank for best access to the radiator cap and top of the radiator.

2. Drain the Old Coolant

  • Place a drain pan under the water pump area. The 10mm drain bolt (often with an aluminum or copper washer) is located at the lowest point of the water pump cover.
  • Loosen the radiator cap to relieve residual pressure. Then fully remove the drain bolt and allow all coolant to drain. Some models may have an additional drain screw on the radiatorcheck and remove it if present.
  • Once drained, reinstall the drain bolt with a new washer for best sealing.

3. Flush the System (Recommended)

  • With the drain bolt reinstalled, fill the radiator with distilled water. Reinstall the cap and run the engine brieflyjust long enough to circulate the water (do not overheat).
  • Shut off the engine, let it cool, and drain the water by removing the drain bolt again. Repeat until the drained water runs clear.

4. Add New Coolant

  • With the drain bolt installed, fill the radiator slowly with a 50/50 premixed ethylene glycol coolant until the level reaches the filler neck. This mixture ensures protection against corrosion and maintains the correct boiling point for off-road riding.
  • Leave the radiator cap off and start the engine. Let it idle, and watch for air bubbles escaping. Gently rock the bike side to side to help air escape the system.
  • When the bubbles stop, turn off the engine and top off the radiator. Reinstall the cap securely.

5. Check Coolant Level and Inspect for Leaks

  • After the engine fully cools, recheck the coolant level and top off as needed. Inspect the entire system for leaks at the drain bolt, hoses, and radiator seams. Tighten clamps as necessary.

Special Notes for 1987 CR250 Owners

  • The 1987 CR250 features an aluminum radiator, so always use ethylene glycol coolant formulated for aluminum. Avoid silicate-containing coolants, as they can damage internal passages over time.
  • This model's cooling system volume is relatively small. Overfilling can cause pressure buildup and force coolant out of the overflow during operation.
  • Check your radiator cap's condition. A weak spring or old gasket can reduce pressure, causing premature boil-overreplace if uncertain.
  • If you race or ride hard, periodically inspect radiator fins and ensure airflow is unobstructed. Dirt and bent fins can impede cooling efficiency.

By following these steps, you can keep your 1987 Honda CR250 performing at its best. Consistent cooling system care is essential for classic two-strokesRide safe and keep your machine running cool.

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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.