How to Change the Coolant in a 1999 Yamaha TTR250

Shop parts for a 1999 Yamaha TTR250 Dirt Bike.

Changing the coolant on your 1999 Yamaha TTR250 is essential maintenance ensuring reliable engine performance & longevity, especially for off-road riders. As a unique, air/oil-cooled dirt bike with a durable design, the TTR250 benefits from routine cooling system service to prevent overheating on long rides or tough trails. Here's a comprehensive, MotoSport-exclusive guide to the process–no prior experience required.

Tools & Supplies

  • Pre-mixed motorcycle coolant (or concentrate + distilled water)
  • Phillips & flathead screwdrivers
  • Socket wrench & appropriate sockets (for drain bolt & plastics)
  • Drain pan
  • Replacement sealing washer (recommended)
  • Funnel
  • Clean rags or shop towels
  • Gloves & eye protection

Step-by-Step Instructions

  1. Let the bike cool completely. Never open a hot radiator–the system is under pressure and can cause burns.
  2. Remove necessary bodywork. Take off the seat & side panels for easier access to the radiator cap and overflow reservoir.
  3. Open the radiator cap. Slowly release the pressure, then remove the cap. Locate the coolant reservoir as well.
  4. Find the coolant drain bolt. Typically located on or near the water pump on the TTR250. Place a drain pan underneath.
  5. Drain the coolant. Remove the drain bolt and allow old coolant to fully escape. Open the overflow tank if accessible and disconnect its hose to drain any residual liquid.
  6. Inspect and clean. Check the old coolant for signs of oil, rust, or debris (evidence of other issues). Wipe away any residue from the radiator neck, tank, and drain area.
  7. Replace the washer and re-install drain bolt. Use a new sealing washer for best results, and tighten the drain bolt securely.
  8. Fill with new coolant. Slowly pour pre-mixed coolant into the radiator using a funnel. Avoid "glugging" to minimize trapped air bubbles. Fill until coolant reaches the base of the filler neck.
  9. Top up the overflow reservoir. Fill to the "upper" mark, then reinstall its cap and reconnect hoses securely.
  10. Bleed the system. With radiator cap off, start the engine and let it idle for several minutes. Gently rev or rock the bike–this helps eliminate air pockets ("burping"). Watch for the coolant level dropping as air escapes. Add coolant as needed until stable.
  11. Final check. Once air is out and the flow is steady, reinstall the radiator cap. Let the engine heat cycle fully, then cool entirely, and double-check both radiator and reservoir levels. Top up again if needed.
  12. Reinstall plastics and clean up. Dispose of used coolant responsibly, as it's toxic to animals and the environment.

Special Notes for the TTR250

  • TTR250's cooling fins and radiator are designed for harsh off-road conditions; thorough cleaning is advised whenever you change coolant, as mud and debris can accumulate on external components.
  • Only use motorcycle-specific, silicate-free coolant. Standard automotive coolants can cause deposits or accelerated wear on seals.
  • Inspect for leaks under pressure and check that all hose clamps are secure before your next ride.
  • If you notice frequent overheating or persistent low coolant on this model, inspect the water pump and radiator cap for wear–common failure points on older TTRs.

Maintenance Tips

  • Replace coolant every two years or per your service manual, even if it looks clean. Coolant degrades chemically over time.
  • Check fluid levels regularly, as rough terrain can cause small leaks or evaporation.

With these steps, your 1999 Yamaha TTR250's cooling system will be fresh and ready for any trail or adventure ahead. Proper coolant changes extend engine life and reliability, keeping you on the ride and off the repair bench.

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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.