How to Change the Coolant in a 1979 Suzuki RM80

Shop parts for a 1979 Suzuki RM80 Dirt Bike.

Keeping your 1979 Suzuki RM80 running at peak performance starts with proper maintenance, and that includes changing the coolant regularly. While the RM80 is a simple and reliable two-stroke machine, neglecting the cooling system can lead to overheating, premature wear, or engine failure. Here&s a model-specific, step-by-step MotoSport guide to changing the coolant in your vintage RM80.

What Makes the 1979 RM80 Unique?

The 1979 RM80 was built with a compact, air-cooled engine that uses a wave disc water pump to circulate coolant through its small radiator system. Because these bikes are aging, seals and gaskets are prone to leaks and should be inspected every time you change the coolant. Many owners now encounter original parts, so be gentle with old plastics and aluminum components during the process.

Before You Start

  • Work on a cold engine to avoid burns.
  • Have a drain pan, a funnel, OEM-recommended coolant (silicate-free), distilled water, and basic hand tools ready.
  • Inspect radiator hoses and clamps for cracks or wear during the job.

Step 1 – Remove the Old Coolant

  • Prop your RM80 on a stand for stability.
  • Remove the radiator cap slowly to relieve pressure.
  • Locate the coolant drain bolt on the water pump cover near the lower right side of the engine. Place your drain pan underneath and remove the bolt completely. Let all old coolant drain out.
  • If desired, remove the radiator hose at the lowest point for additional drainage.

Step 2 – Flush the System (Recommended)

  • Reinstall the drain bolt temporarily and fill the radiator with distilled water.
  • With the radiator cap still off, briefly start the engine (20–30 seconds) to circulate the water and help flush debris. Shut off immediately.
  • Drain all flush water.
  • Repeat if the drained water still appears dirty.

Step 3 – Refill with Fresh Coolant

  • Reinstall and snug the drain bolt (replace the sealing washer if needed).
  • Pour the correct mix of coolant and distilled water (50/50 unless otherwise specified) into the radiator slowly, allowing air to escape.
  • Gently rock or tap the bike to help release trapped air.
  • Fill up to the base of the filler neck, then install the cap.

Step 4 – Bleed Air from the System

  • Start the bike and run it until the engine is warm. Watch the coolant level drop as air works out—shut off the engine as needed and top off the radiator if the level drops.
  • With no dedicated bleeder fitting, the RM80 relies on running and rechecking fluid after cooling down.
  • Check for leaks at the hose and cover joints, especially around the aging water pump seal. If leaks persist, replace the seal and gasket before riding.

Final Checks

  • Let the bike cool fully, remove the cap, and top up again if needed.
  • Recheck coolant level before your next ride.
  • Dispose of old coolant responsibly, as it is toxic to animals.

RM80 Coolant Maintenance Tips

  • Inspect the water pump impeller and shaft periodically—older seals and bearings can cause leaks visible at the weep hole or under the right engine cover.
  • The 1979 model's compact system means trapped air is a common cause of overheating, so be thorough bleeding all air out.
  • Replace hoses and clamps if they show any signs of age or deterioration.

This guide will help you bring your Suzuki RM80 back to reliable trail or track performance. For replacement hoses, seals, gaskets, or upgraded coolant, MotoSport has all the 1979 RM80 parts you need.

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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.