How to Change the Coolant in a 2013 Yamaha YZ125
Shop parts for a 2013 Yamaha YZ125 Dirt Bike.
Proper cooling is essential for sustained performance and longevity in your 2013 Yamaha YZ125. Regular coolant changes help protect the lightweight two-stroke engine from overheating, corrosion, and sediment buildup. This step-by-step, MotoSport-exclusive guide covers everything you need to know for a safe and effective coolant change, as well as model-specific considerations for the YZ125 owner.
Essentials Before You Begin
- Ensure the engine is completely cool before starting—never remove the radiator cap from a hot engine to avoid serious burns from pressurized coolant spray.
- Position your YZ125 on a level surface and hold it upright using a stand or helper.
- Have a drain pan ready to catch old coolant, and arrange access to clean, soft or distilled water for flushing if needed.
- Required tools: 10mm wrench or socket (for the drain bolt), fresh coolant (meeting Yamaha specifications), clean rags, and safety gloves.
Step-by-Step Coolant Change
- Remove the Radiator Cap
With the bike upright, open the radiator cap slowly by pressing down and turning counterclockwise. Listen for any pressure release and wait until hissing stops before fully removing the cap. - Drain Old Coolant
Locate the coolant drain bolt (at the water pump or lower radiator hose). Place your drain pan below the engine and remove the drain bolt, along with its copper washer. Let the coolant flow out completely. - Flush the Cooling System (Recommended)
If coolant is dirty, flush the radiator and engine by pouring clean, distilled (or soft) water into the filler neck. Replace the drain bolt and tighten to 10 Nm (–7.2 ft-lb); refill, shake the bike gently to agitate, then drain the water out again. Repeat until only clean water flows. - Reinstall Drain Bolt
Reattach the drain bolt and a new washer if necessary. Tighten the bolt to the manufacturer's recommended torque (10 Nm or 7.2 ft-lb). - Fill with New Coolant
Slowly pour in fresh coolant until it reaches the specified level. Use coolant compatible with aluminum components and pre-mixed if possible. Do not overfill—the correct level is usually visible at the radiator's filler neck. - Bleed Air from the System
Tip the bike lightly from side to side to help air pockets escape. Some owners momentarily loosen the drain bolt or hoses to burp stubborn air, but always tighten to torque spec afterward. - Check for Leaks & Top Up
With the radiator cap still off, briefly start the engine and let it idle for 30 seconds. Shut the engine down, check the coolant level, and top off if necessary. Securely refit the radiator cap. - Dispose of Old Coolant Properly
Never pour used coolant down a drain or onto the ground. Take it to a local recycling center or hazardous waste facility.
YZ125 Owner Notes & Tips
- YZ125 radiators and water pumps are compact and can be sensitive to impact or residue build-up. Inspect hoses and the radiator for any damage or corrosion when changing your coolant.
- Keep coolant off painted or plastic surfaces—if a spill occurs, rinse immediately with water to avoid staining or damage.
- For the 2013 YZ125, avoid hard or mineral-rich water in the system, as it can harm internal engine components. Distilled water is best for flushing.
- If switching to a different coolant type (such as from conventional to a non-water-based solution), flush the system thoroughly to remove all traces of the old coolant.
- Replace the radiator cap if its seal is brittle or damaged—a pressure leak here can trigger overheating.
Changing the coolant in your 2013 Yamaha YZ125 not only extends the life of your engine but keeps you riding at peak performance. Keep these factory-backed tips in mind, and always use high-quality, compatible parts and coolants for best results. For maintenance, replacement parts, or performance upgrades, MotoSport is your trusted source for everything YZ125.
Related Shopping Categories
Shop Radiators for a 2013 Yamaha YZ125 Dirt Bike.
Shop Coolant for a 2013 Yamaha YZ125 Dirt Bike.
Shop Temperature Sensors for a 2013 Yamaha YZ125 Dirt Bike.
Shop Tools for a 2013 Yamaha YZ125 Dirt Bike.
Shop Radiator Hoses for a 2013 Yamaha YZ125 Dirt Bike.
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.