How to Change the Coolant in a 2018 Yamaha YZ85: A MotoSport Guide
Shop parts for a 2018 Yamaha YZ85 Dirt Bike.
Routine coolant changes are crucial for the high-revving, liquid-cooled two-stroke engine of your 2018 Yamaha YZ85. This mini motocross machine is designed for young racers but demands the same precision maintenance as full-size bikes. Follow this exclusive MotoSport step-by-step guide for safe, effective coolant replacement – with specific tips for your MMY (Make, Model, Year) bike.
What You Need Before You Start
- Fresh coolant (check your owner's manual for type, but a quality ethylene glycol-based motorcycle coolant is standard)
- Drain pan or container to catch old coolant
- 8mm and 10mm sockets or wrenches
- Funnel
- Distilled water (for flushing, not always strictly necessary)
- Clean rags
- Gloves and eye protection
Step-by-Step: Changing the Coolant
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Let the Engine Cool
Always make sure the bike is completely cool before starting. A hot system is under pressure – opening the radiator cap too soon could cause burns or sprays. -
Stabilize and Access
Place the bike on a stand or level surface.
Remove the radiator cap to release any pressure. -
Drain the Old Coolant
- Locate the coolant drain bolt – it's typically on the water pump cover (right side of the engine).
- Place your pan underneath, then remove the drain bolt along with its small sealing washer or gasket.
- Let coolant fully drain out. Briefly tilting the bike side to side can help remove all old fluid.
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Flush the System (Recommended)
- For optimal cleaning, pour distilled water into the radiator, replace the drain bolt, and let the water flush through. Repeat until water comes out clear.
- Drain one final time to remove all flush water.
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Reinstall the Drain Bolt
- Always use a new washer or gasket for the drain bolt to prevent leaks.
- Tighten snugly, but do not over-tighten as the water pump cover is aluminum and threads can strip.
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Refill with Fresh Coolant
- Using a funnel, slowly pour the new coolant into the radiator until it reaches the top.
- Tap or gently rock the bike to release trapped air bubbles and top off as needed.
- Reinstall and tighten the radiator cap.
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Check for Leaks & Burp the System
- Start the engine and let it idle briefly. Watch for leaks at drain bolt and hoses.
- After a few minutes, turn off and let cool – check coolant level again, topping off if needed.
YZ85-Specific Tips & Notes
- The YZ85's high-output engine runs hot, so maintaining clean, fresh coolant is vital for top performance and avoiding boil-overs.
- Coolant leaks around head bolts can indicate a failing head gasket or improperly torqued bolts. Address any dampness or seepage early to avoid bigger repairs.
- Always use the correct coolant blend. Mixing incompatible types can cause gelling and clogged passages.
- Inspect hoses and radiator for signs of wear or trampling, especially after racing or crashes.
Final Check
- Monitor the coolant level periodically, especially during hot track days or hard trail riding.
- If you notice overheating, visible leaks, or cloudiness in the coolant, perform a flush and inspect the cooling system thoroughly.
Stay ahead of maintenance and keep your 2018 Yamaha YZ85 ripping with routine coolant changes—and always trust MotoSport for top parts and fluids made to withstand your toughest rides.
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Shop Radiator Hoses for a 2018 Yamaha YZ85 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.