How to Change the Coolant in a 1997 KTM 360SX

Shop parts for a 1997 KTM 360SX Dirt Bike.

Changing the coolant in your 1997 KTM 360SX is a key maintenance task that prevents overheating and ensures optimal engine performance. Below is a MotoSport-exclusive guide that takes you step-by-step through the process, highlighting essential model-specific notes for your vintage two-stroke KTM.

What You Need

  • Fresh coolant (ethylene glycol-based; motorcycle-specific recommended)
  • Distilled water (for flushing, optional but recommended)
  • 8mm socket or wrench
  • Drain pan or bucket
  • Funnel
  • Torch wrench (if available, for precise assembly)
  • Clean rag
  • Protective gloves

Preparation Steps

  • Allow the engine to fully cool before starting. Hot coolant can cause severe burns.
  • Stand the bike upright on a level surface or work stand.
  • Wipe dirt and debris from the area around the radiator cap and water pump to prevent contamination.

Draining the Coolant

  • Remove the radiator cap. This is located at the top of the left radiator. Opening the system first relieves vacuum and allows full drainage.
  • Position your drain pan under the water pump cover (right side, lower engine area).
  • Locate the coolant drain bolt – for the 360SX, there is usually a small 8mm bolt on the lower edge of the water pump cover. Loosen and remove it. Coolant will begin to drain quickly.
  • Let all coolant drain. Slightly tilting the bike side-to-side helps empty both radiators.
  • For a more thorough flush, re-install the drain bolt, fill the system with distilled water, run the engine briefly (1-2 min), then repeat the drain process.

Reinstalling Drain Bolt

  • Inspect the drain bolt washer or sealing ring; replace if damaged to avoid leaks.
  • Torque the drain bolt to manufacturer spec (typically around 8 Nm for KTM water pumps, but verify in your KTM manual if possible).

Refilling with Coolant

  • Slowly pour fresh coolant into the radiator using a funnel. The 360SX holds approximately 1-1.1 liters of coolant. Fill until the radiator is full and coolant reaches the bottom of the filler neck.
  • If equipped, open the small bleeder screw (sometimes on the thermostat housing or top radiator, depending on year and market) while filling. Once coolant flows bubble-free from the bleeder, close it.

Bleeding the Cooling System

  • With the radiator cap off, briefly start the engine and allow it to idle for a minute. Gently rock the bike side to side to release trapped air.
  • Switch off, top off coolant as needed, then reinstall the radiator cap securely.
  • If the 360SX is equipped with a secondary coolant reservoir, check and top up to the max line.

Final Checks

  • Start the engine and let it reach operating temperature. Watch for leaks and monitor the temperature for any signs of overheating.
  • Once cool, recheck coolant level and top up if necessary.

Special Notes for the 1997 KTM 360SX Owner

  • Unique cooling system– The 360SX uses a proven open-loop radiator setup. Its two-stroke engine generates significant heat under load, so keeping coolant fresh is critical for race use and hard trail riding.
  • Vintage plastics– The radiator shrouds and plastics on these older bikes are prone to wear and cracking. Take extra care when removing or reinstalling them around the radiators.
  • Gasket care– The age of the model means seals at the water pump and radiator hoses may be original. Inspect for cracks or swelling—replace with MotoSport parts if needed to avoid leaks.
  • Coolant choice– Avoid mixing coolant types. KTM recommends ethylene glycol motorcycle coolant; never use pure water or automotive coolant blends.

Maintaining your 360SX with regular coolant changes keeps this classic MX machine performing at its best. For replacement hoses, radiators, or fresh coolant, MotoSport is your go-to source for OEM and high-performance upgrades tailored to your bike.

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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.