How to Change the Coolant in a 2017 Yamaha YZ125
Shop parts for a 2017 Yamaha YZ125 Dirt Bike.
Changing the coolant in your 2017 Yamaha YZ125 is a key part of regular maintenance–crucial for preventing overheating and protecting your engine from damage. The process is straightforward, but attention to detail ensures the job is done right, especially for a high-revving two-stroke like the YZ125.
Tools & Supplies Needed
- Socket set and screwdrivers
- Drain pan
- Coolant compatible with aluminum engines
- Clean rags
- Funnel
- Optional: compressed air and distilled water for flushing
Step-by-Step Coolant Change Procedure
- Let the engine cool completely. Never remove the radiator cap when the engine is hot–pressure and hot coolant can cause injury or burns.
- Remove the radiator cap. Locate it on the left side at the top of the radiator. Twist counterclockwise to release it.
- Locate the coolant drain bolt. On the 2017 YZ125, this is typically at the bottom of the water pump cover on the right side of the engine. Place a drain pan underneath.
- Loosen the drain bolt and allow the coolant to flow out. Also loosen the radiator cap fully to allow air in and speed up draining. Some riders remove the lower radiator hose for a more complete drain.
- Inspect the drained coolant. Old, murky, or rusty-looking fluid can indicate it was overdue for a change.
- To flush (recommended): Reinstall the drain bolt. Fill the radiator with distilled water, then run the engine briefly (under a minute) to circulate. Let cool, remove the drain bolt, and drain the water. Repeat until the water runs clear.
- Ensure all water or old coolant is drained. Use compressed air to blow through the radiator hoses for a thorough flush if desired.
- Reinstall drain bolt and secure tightly. Double-check for any signs of wear or leaking.
- Fill radiator with fresh coolant. Use a funnel and fill to the base of the cap neck, as recommended by Yamaha.
- Bleed air from the system. Rock the bike gently side to side and squeeze the hoses by hand. Top off coolant as needed.
- Reinstall the radiator cap securely.
- Start the engine and run for several minutes. Monitor for leaks and recheck the coolant level after the bike has cooled. Add coolant if necessary.
What Every 2017 YZ125 Owner Should Know
- Cylinder and radiator design: The YZ125 has a narrow two-stroke engine and minimal coolant system, so keeping the system topped up and free of air bubbles is vital for performance and longevity.
- Coolant Type: Yamaha recommends a high-quality ethylene glycol coolant designed for aluminum engines. Avoid mixing coolant types; always flush the system if trying a new coolant formula.
- Drain Interval: Replace coolant at least once a year or more often under heavy/race use–it degrades over time and loses effectiveness.
- Inspection: Use this opportunity to inspect radiator hoses, clamps, and for any fin damage or leaks. The YZ125 radiator is exposed during off-road use and is susceptible to impacts.
Routine coolant changes guard against corrosion, overheating, and keep your YZ125 running strong moto after moto. A few basic tools and some attention to detail will reward you with a cool, reliable ride all season long.
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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.