How to Change the Coolant in a 1985 Yamaha XT350

Shop parts for a 1985 Yamaha XT350 Dirt Bike.

Changing the coolant on your 1985 Yamaha XT350 keeps your engine running at peak performance and prevents overheating, especially during intense trail rides or summer heat. This model features a liquid-cooled single-cylinder engine, which relies on a properly maintained cooling system for long-term durability. Follow this MotoSport-exclusive step-by-step guide to ensure a proper coolant change and to extend the life of your classic dirt bike.

Tools & Supplies Needed

  • New coolant (use motorcycle-specific, not automotive antifreeze)
  • Distilled water
  • Drain pan
  • Sockets or wrenches (for drain bolt and any covers)
  • Funnel
  • Gloves and rags

Step 1 – Cool Down and Prepare

Ensure the XT350 is completely cool before starting. Remove the seat and tank shrouds, if necessary, to easily access the radiator cap and drain bolt. Place the bike on a stable stand.

Step 2 – Drain the Old Coolant

  • Locate the coolant drain bolt at the bottom side of the water pump cover.
  • Position a drain pan underneath.
  • Remove the radiator cap first to allow air in, then loosen and remove the drain bolt (and sealing washer), allowing old coolant to flow out.
  • If the XT350 has a coolant reservoir tank, drain it as well by removing the lower hose.

Step 3 – Flush the System (Optional but Recommended)

  • With the drain bolt still out, pour distilled water into the radiator to flush contaminants and old coolant residue.
  • Reinstall the drain bolt with a fresh sealing washer. Tighten to factory specs.

Step 4 – Add New Coolant

  • Using a funnel, slowly pour new coolant into the radiator until it reaches the base of the filler neck.
  • If your coolant requires mixing, use a 50/50 blend of coolant and distilled water. Premixed coolants can be added directly.
  • Fill the reservoir to the full line if equipped.

Step 5 – Bleed the Cooling System

  • With the radiator cap off, briefly start the engine and let it idle. Blip the throttle and gently rock the bike side to side to help air escape from the system.†
  • Watch for air bubbles and top off coolant as needed.

Step 6 – Re-Check Levels

  • Turn the engine off and allow it to cool completely.
  • Re-check coolant level in both the radiator and the reservoir. Top off if needed—the system may pull in more coolant as it heats and cools.

Step 7 – Reassemble & Clean Up

  • Reinstall and secure any parts or bodywork removed earlier.
  • Dispose of old coolant responsibly. Used antifreeze is hazardous—take it to a recycling center or auto parts store.

XT350 Model Notes and Tips

  • The 1985 XT350 features a compact radiator vulnerable to clogs and dirt; keep radiator fins clear and undamaged for optimal cooling.
  • Inspect hoses and clamps regularly. Due to the age of this model, rubber cooling hoses may become brittle and should be replaced if cracked or swollen.
  • Factory service intervals suggest coolant renewal every two years or as indicated in your owner's manual – consider changing it annually for hard off-road use.
  • The Yamaha XT350's engine runs hotter during technical off-road riding; a well-maintained cooling system is crucial to prevent engine damage.

With correct coolant maintenance, your 1985 XT350 stays reliable and ready for the next adventure.

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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.