How to Change the Coolant in a 2009 Yamaha YZ85
Shop parts for a 2009 Yamaha YZ85 Dirt Bike.Changing the coolant in your 2009 Yamaha YZ85 is crucial for keeping the engine running cool under the rigors of off-road riding. This model boasts a high-revving, liquid-cooled 2-stroke engine with a compact radiator, so routine cooling system maintenance directly affects its performance and reliability. Here is a step-by-step guide made just for MotoSport.com readers.
What You Need
- Fresh coolant (check user manual for recommended type–avoid mixing types)
- Funnel
- Drain pan
- Clean filtered or distilled water for flushing
- Socket wrench or spanner (for drain bolt)
- Rags for cleanup
- Safety gloves
Step-by-Step Coolant Change Process
- Let the engine cool completely to avoid burns. Ensure the YZ85 is on a stand for stability.
- Remove the radiator cap slowly to relieve any residual pressure.
- Locate the coolant drain bolt (generally situated at the bottom of the water pump cover on the left side of the engine). Place the drain pan underneath.
- Remove the drain bolt–coolant will begin to flow out. Let it drain fully. To help it empty faster, tip the bike slightly and ensure the radiator cap is fully removed for airflow.
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Flush the system (recommended) by reinstalling the drain bolt temporarily and pouring filtered/distilled water through the radiator until the fluid runs clear from the drain. Remove the bolt again to let water out before final fill.
Filtered or distilled water prevents mineral deposits in the narrow YZ85 cooling channels. - Reinstall the drain bolt and torque it to spec (do not overtighten–the YZ85 case is soft and easy to strip).
- Fill the radiator with new coolant using a funnel for accuracy. Fill to the base of the neck, checking the level as you go.
- Reinstall the radiator cap securely.
- Run the engine for a few minutes with the bike upright to circulate coolant and purge air bubbles. Shut down, let it cool, and recheck the coolant level at the cap–top off as needed.
- Inspect for leaks around the drain bolt and radiator hoses.
What Every 2009 YZ85 Owner Should Know
- The YZ85 has a small-capacity cooling system–air bubbles easily get trapped, so always recheck the coolant level after the first heat cycle.
- If you ride in mud or deep sand, inspect and clean the radiator fins regularly–overheating risks rise when airflow is restricted.
- Never use tap water for flushing or mixing with coolant; minerals will quickly scale the radiator and passageways.
- Replace coolant every season or after heavy riding in harsh conditions for maximum engine protection.
Following these steps ensures your 2009 YZ85 runs at peak performance, keeping engine temperature in check for every ride.
Related Shopping Categories
Shop Radiators for a 2009 Yamaha YZ85 Dirt Bike.
Shop Coolant for a 2009 Yamaha YZ85 Dirt Bike.
Shop Temperature Sensors for a 2009 Yamaha YZ85 Dirt Bike.
Shop Tools for a 2009 Yamaha YZ85 Dirt Bike.
Shop Radiator Hoses for a 2009 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.