How to Change the Coolant in a 1987 Kawasaki KX80

Shop parts for a 1987 Kawasaki KX80 Dirt Bike.

The 1987 Kawasaki KX80 remains a beloved classic in the world of 2-stroke dirt bikes. Regular coolant replacement is essential to maintain optimal engine temperature and extend the life of your bike. Swapping the coolant helps prevent overheating, corrosion, and internal engine damage—particularly critical for an older model like the KX80. Below is a proprietary MotoSport guide for changing the coolant on this vintage machine, with tips unique to this model year.

What You Need

  • Fresh, high-quality coolant designed for motorcycles
  • Drain pan
  • Socket or wrench (typically 8mm for drain bolt)
  • Funnel
  • Distilled water (if flushing)
  • Gloves and safety glasses
  • Clean shop rags

Preparation

  • Ensure the engine is completely cool to avoid burns; hot coolant can cause severe injury.
  • Park your KX80 on a stable, level surface and support it with a stand.
  • Remove the seat and left side panel as needed for radiator access.

Drain the Old Coolant

  • Locate the coolant drain bolt on the lower side of the water pump cover (right side of the crankcase).
  • Place a drain pan beneath the bolt and slowly remove it. Also remove the radiator cap to allow the coolant to flow freely.
  • Allow all coolant to drain. For a more thorough flush, pour a small amount of distilled water into the radiator and let it drain out as well, especially if swapping coolant types.

Inspect System – Specific to 1987 KX80

  • Check all radiator hoses and clamps for cracks or leaks. The 1987 KX80 is susceptible to cracks at the hose ends due to age.
  • Visually inspect the water pump weep hole area for any signs of leakage—a common issue on older KX engines. Persistent leaks likely mean a failing water pump seal.

Refill with Fresh Coolant

  • Reinstall the drain bolt and torque it to factory spec. Do not overtighten to avoid stripping the threads—an increased risk with aluminum casings of vintage bikes.
  • Using a funnel, slowly pour new coolant into the radiator until it's just below the filler neck.
  • Gently rock the bike side to side to release trapped air bubbles.

Bleed Air from the System

  • Leave the radiator cap off and start the engine; allow it to idle for a minute while watching the coolant level. Top off as needed, since air pockets may escape.
  • Once the bubbling stops and the coolant reaches just under the filler neck, install the radiator cap securely.

Check for Leaks & Test Ride

  • Inspect for leaks around the drain bolt, hoses, and radiator. Wipe up any spills.
  • After a short test ride and cooling period, double-check the coolant level and top off if needed. The vintage KX80's compact cooling system leaves little margin for error.

Model-Specific Notes

  • The 1987 KX80 uses a simple, open cooling system without an overflow tank; monitor the coolant level directly in the radiator.
  • Always use silicate-free motorcycle coolant to preserve the classic Kawasaki magnesium engine cases.
  • Failure to change coolant regularly can accelerate corrosion—a notable issue in older Kawasaki 2-strokes.

With routine coolant changes, your 1987 KX80 will stay running cool and strong, ready for more laps at the track or trails. Protect your classic — and see noticeable gains in performance consistency and reliability.

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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.