How to Change the Coolant in a 2025 GAS GAS MC85BW
The 2025 GAS GAS MC85BW (Big Wheel) is a next-generation youth motocross machine engineered for high performance, featuring a re-engineered chassis, upgraded cooling system, and a powerful 84.9cc 2-stroke engine with a Keihin PWK 28 carburetor. With brand new radiators designed to ensure ideal engine temperatures, regular coolant changes are essential to maintain optimal power and reliability–especially on a competition-oriented model like this.
What Makes the MC85BW Cooling System Special?
The MC85BW for 2025 includes newly developed PANKL radiators specifically tuned for improved flow and heat exchange. Combined with changes to the cylinder head, airbox, and a repositioned engine for better balance, this system keeps the engine performing at peak levels.
Signs It–s Time to Change the Coolant
- Coolant appears cloudy, discolored, or dirty
- The engine is running hotter than normal or overheating
- You–ve reached the recommended maintenance interval (at least once per season or after 20-40 hours of use for a race bike)
Required Tools & Supplies
- Fresh high-quality motorcycle coolant (make sure it is compatible with aluminum radiators and 2-stroke motocross engines)
- Flathead screwdriver or socket set
- Drain pan
- Funnel
- Clean rags
- Protective gloves
Step-by-Step Guide: Changing Coolant on the 2025 GAS GAS MC85BW
- Let the bike cool completely. Never attempt to change the coolant when the engine is hot to prevent burns.
- Remove the seat and side plastic panels as needed. This allows clear access to the radiator cap and hoses.
- Locate the radiator cap. On the MC85BW, this will be on top of the left-side PANKL radiator.
- Position the drain pan below the engine.
- Remove the radiator cap. Slowly loosen the cap to release any residual pressure.
- Find the coolant drain bolt. Typically, this is on the lower side of the water pump cover on the right engine case. Place your drain pan beneath this location.
- Remove the drain bolt and let all coolant drain out. Move the bike side to side gently to ensure complete draining.
- Inspect the coolant and drain bolt. Check for metallic debris or signs of oil mixing, which could indicate further engine issues.
- Reinstall the drain bolt and torque to specification. Use a clean rag to wipe away spills.
- Add new coolant. Using a funnel, slowly fill the radiator until the fluid level sits just beneath the neck and visible through the cap opening. Squeeze the radiator hoses by hand to help burp out air pockets.
- Replace the radiator cap securely.
- Reinstall plastics and seat.
- Start the engine and check for leaks. Allow the engine to warm to operating temperature, then shut off and recheck the coolant level. Top off if needed.
Proprietary Tips for MC85BW Owners
- Never mix different types of coolant; always flush completely if changing brands or types.
- Due to the new radiator and airflow improvements for 2025, air blockages can have a more noticeable impact on cooling performance. Carefully burp the system to remove trapped air after service.
- The lighter frame and redesigned swingarm improve cornering, but keeping the cooling system in top shape ensures the engine delivers maximum performance in these dynamic conditions.
Final Notes
Regular coolant maintenance is crucial for the new 2025 GAS GAS MC85BW to deliver consistent power and reliability all season long. Always use manufacturer-recommended fluids and parts for best results. If you notice any coolant leaks, persistent overheating, or engine performance issues, consult a qualified technician or dealer for inspection.
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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.