How to Change the Coolant in a 2015 Yamaha YZ125
Shop parts for a 2015 Yamaha YZ125 Dirt Bike.
Maintaining the cooling system on your 2015 Yamaha YZ125 is critical for reliable engine performance, especially during hard riding and racing. Regular coolant replacement helps prevent overheating and corrosion, keeping your two-stroke running at peak efficiency. The following guide offers step-by-step instructions tailored for your model, along with important details specific to the YZ125.
What Makes the 2015 YZ125 Cooling System Unique?
- Uses a lightweight, high-capacity aluminum radiator system tailored for motocross conditions
- Requires strict attention to coolant type–aluminum-safe, ethylene glycol with anti-corrosive properties only
- Coolant capacity: 0.95 L (1.00 US qt)–do not overfill
Required Tools & Supplies
- 10mm wrench or socket
- Container to catch old coolant
- Soft clean rags
- High quality ethylene glycol-based coolant (aluminum-safe, pre-mixed 50/50 or mixed with soft water)
- New copper washer (recommended for drain bolt)
- Pair of gloves and eye protection
Step-by-Step Coolant Change Instructions
- Allow the bike to cool completely to prevent scalding from hot coolant or pressurized system.
- Support the bike upright on a stand. Remove the radiator shrouds to access the radiator cap.
- Place a drain container under the engine.
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Remove the radiator cap slowly to relieve any pressure.
Tip: Removing it slowly will help avoid sudden spurts of coolant. - Locate and remove the coolant drain bolt on the right side of the cylinder and let the old coolant flow into your container. Inspect the copper washer; replace if worn.
- Flush the system (recommended): Pour clean, soft water into the radiator and let it drain to remove contaminants. Repeat as needed until water runs clear.
- Reinstall the drain bolt (with a new copper washer); torque to 10 Nm (7.2 ft–lb) for a proper seal.
- Pour fresh coolant into the radiator up to the filler neck. For best results, use a 50/50 mix of ethylene glycol coolant and soft water, specifically designed for aluminum engines.
- Tap the radiator hoses gently to release air bubbles, then refill as needed to the appropriate level.
- Reinstall the radiator cap securely.
- Start the engine with the radiator cap on. Let it idle for a few minutes, then shut off and let cool. Re-check coolant level and top off if necessary.
Additional Tips for 2015 Yamaha YZ125 Owners
- Check for leaks around all hose clamps, the cap, and the drain bolt after completing the job.
- Ensure only aluminum-compatible coolant is used–avoid silicate-containing coolants that can damage internal components.
- Avoid using hard water in the mix, which can leave mineral deposits and reduce cooling efficiency.
- Regular coolant changes (once per season or per manufacturer recommendation) help maintain system health.
Proper care of your 2015 Yamaha YZ125 cooling system not only protects your engine but gives you the confidence for your next track or trail adventure. For OEM and aftermarket parts, trusted fluids, and tools, shop parts for a 2015 Yamaha YZ125 Dirt Bike.
Related Shopping Categories
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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.