How to Change the Coolant on a 1981 Yamaha IT250

Shop parts for a 1981 Yamaha IT250 Dirt Bike.

Keeping the coolant fresh in your 1981 Yamaha IT250 is essential for optimal engine performance and longevity. The IT250’s liquid-cooled engine relies on a robust cooling system to handle the rigors of off-road riding. Regular coolant changes help prevent overheating, corrosion, and internal component wear–vital for a two-stroke like the IT250, which can run hot under stress.

What Makes the 1981 Yamaha IT250 Cooling System Unique?

Unlike many modern four-strokes, your IT250 uses a simple, efficient radiator system that was ahead of its time. The radiator and cooling passages should be clear of debris and mineral deposits to maintain proper flow. This model typically holds around 1.2 liters of coolant, so have the correct volume ready before starting the process. Always use a high-quality, ethylene glycol-based antifreeze with anti-corrosion agents for aluminum engines, premixed 50/50 with distilled water for best results–see below for details –hard or tap water may cause scaling or deposits inside the radiator and engine block.

Step-by-Step: Coolant Change Procedure for the IT250

  • Preparation: Ensure your engine is completely cool before starting. Place the motorcycle on a stable stand. Gather a drain pan, socket or allen set for bolts, funnel, and fresh coolant (premixed or mix your own with distilled water).
  • Drain the Old Coolant:
    • Locate the coolant drain bolt, usually found at the lowest point of the engine side cover or near the water pump area.
      Loosen and remove this bolt (be sure to replace or inspect the copper sealing washer for damage).
    • Remove the radiator cap to allow the system to vent and drain completely into your pan.
  • Flush the System:
    • After draining, flush the cooling system with distilled water until it runs clear. If your system looks particularly dirty or you've bought the bike used, consider a 50/50 mix of water and white vinegar for a single flush, then rinse thoroughly with distilled water before refilling.
  • Refit Drain Bolt:
    • Reinstall and tighten the coolant drain bolt to the recommended torque (about 10 Nm or 7.2 ft–lb).
  • Refill with Coolant:
    • Using a funnel, slowly pour your new coolant mix into the radiator up to the base of the filler neck. Total system capacity is approximately 1.2 liters.
    • If equipped, fill the overflow reservoir to the upper line.
  • Bleed Air from the System ("burp" the radiator):
    • Start the engine with the radiator cap off. Let it idle and gently rev a few times. This helps trapped air escape.
    • Top off coolant as needed. Once air bubbles cease, turn off the engine and let cool completely. Check the level again and top up if required.
  • Reinstall the Radiator Cap & Inspect:
    • Once you’re sure levels are topped and air is purged, securely reinstall the radiator cap.
    • Inspect for leaks. Dispose of old coolant safely.

Pro Tips for IT250 Owners

  • Check for signs of corrosion or scaling in the radiator.
    If detected, more thorough cleaning may be needed.
  • Monitor engine temperature after changing coolant. If overheating persists, check for blockages or inspect your water pump and thermostat.
  • The IT250 is prized for its light weight and power, but proper cooling system care is essential for reliability, especially if used in tough or hot environments.

Regularly changing your coolant not only protects your 1981 Yamaha IT250 from internal damage but also keeps your vintage two-stroke running cool and strong for years on the trail.

Related Shopping Categories

Shop Radiators for a 1981 Yamaha IT250 Dirt Bike.

Shop Coolant for a 1981 Yamaha IT250 Dirt Bike.

Shop Temperature Sensors for a 1981 Yamaha IT250 Dirt Bike.

Shop Tools for a 1981 Yamaha IT250 Dirt Bike.

Shop Radiator Hoses for a 1981 Yamaha IT250 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.