How to Change the Coolant in a 1983 Honda CR250: A MotoSport Guide

Shop parts for a 1983 Honda CR250 Dirt Bike.

Routine coolant changes are crucial for keeping your 1983 Honda CR250 running cool – both on the track & the trail. Old or degraded coolant can lead to overheating, performance drops, and even irreversible engine damage. Follow MotoSport’s proprietary step-by-step guide for a safe, efficient coolant service on your classic two-stroke Honda.

What Makes the 1983 CR250 Special?

The 1983 CR250 is a legendary model known for its aluminum components and featherlight chassis. Notably, it sports lightweight aluminum radiators, making it imperative to use only ethylene glycol-based coolant specifically designed for aluminum systems to prevent corrosion and scaling. Overfilling or using the wrong coolant can quickly cause damage.

Tools & Supplies You Need

  • Fresh ethylene glycol-based coolant (for aluminum radiators)
  • Socket or wrench (to remove drain bolt)
  • Drain pan
  • New water pump crush washer, if needed
  • Shop towels
  • Safety gloves & eye protection

Step 1: Prepare Your Workspace

  • Place the bike upright on a stand and let it cool completely.
  • Remove the seat and side panels if easier access to the radiator cap is needed.
  • Set a drain pan beneath the water pump or lowest hose point on the cooling system.

Step 2: Drain the Old Coolant

  • Remove the radiator cap to relieve system pressure.
  • Locate the coolant drain bolt at the water pump cover (left side of engine).
  • Loosen the bolt – old coolant will begin to drain. Remove the bolt fully and let it drain completely.
  • Tip the bike gently side to side to purge trapped coolant. Inspect your old crush washer; replace if required for a leak-free seal.

Step 3: Flush (Optional)

  • For a complete flush, refill the system with distilled water, run the engine for a minute (with the drain bolt temporarily reinstalled), then drain again. Repeat if necessary until the water runs clear.

Step 4: Reinstall Drain Bolt

  • Install new or cleaned crush washer on the drain bolt.
  • Tighten the bolt securely – avoid overtightening, which can strip threads on older bikes.

Step 5: Refill with Fresh Coolant

  • Slowly pour the new coolant into the radiator neck until full. Allow bubbles to escape; gently squeeze coolant hoses to free any trapped air.
  • Fill until the radiator is topped up to the base of the filler neck.

Step 6: Bleed the System

  • Start the engine and let it idle for several minutes with the radiator cap off. Watch for additional bubbles escaping as trapped air works out.
  • If coolant drops, top up to the base of the radiator neck again.
  • Once bubbles stop and coolant is steady, install the radiator cap securely.

Step 7: Heat Cycle & Recheck

  • Run the engine up to operating temperature (until the upper radiator hose is warm).
  • Let the bike cool fully. Remove the cap and re-check coolant level; top off if needed.
  • Check for any leaks at hoses, the drain bolt, and the radiator cap seal.

CR250 Cooling Notes & Expert Tips

  • Use only the recommended coolant type. Universal or silicate-based coolants can corrode your vintage Honda’s radiators.
  • Monitor for pinhole leaks or crusting near the radiators; 1983 units are decades old and may be prone to seam failure from age and vibration.
  • After every coolant change or system service, double-check fasteners after the first heat cycle.
  • If your CR250 is routinely overheating, check for debris blocking radiator airflow or consider an upgraded radiator cap with higher pressure if the stock one is failing.

Keep your vintage 1983 CR250 running cool and crisp by sticking to regular coolant service intervals—and always choose trusted, MotoSport-supplied parts and coolant for peace of mind. Happy riding.

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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.