How to Change the Coolant in a 2025 GAS GAS MC 85
Changing the coolant on your 2025 GAS GAS MC 85 is an essential maintenance task for keeping your bike running cool – especially after hard riding or muddy conditions. While the process shares general steps with other 85cc motocross bikes, the MC 85 does have distinct features and access points every owner should note.
What You Need
- Fresh coolant recommended for motocross 2-strokes
- Basic hand tools (ratchet, sockets, screwdriver)
- Drain pan
- Protective gloves and eyewear
- Rags for cleanup
Step-by-Step Coolant Change Guide
-
Prepare the Bike & Area
Make sure the engine is completely cool. Park the MC 85 on a level surface and place the drain pan underneath the engine and radiator area. -
Remove Radiator Cover
Remove the radiator side shrouds or covers for clear access to the radiator cap, hoses, and bleed points. Check that no dirt or debris is present near the filler neck or cap. -
Drain the Old Coolant
Locate the coolant drain bolt – typically on the lower part of the water pump cover on the right side of the engine. Open the radiator cap to help coolant flow, then use a socket to loosen and remove the drain bolt. Allow all fluid to drain into the pan.
Inspect the drained coolant for signs of contamination or metallic particles. -
Flush If Needed
For a thorough change, flush the system with clean water – never use chemical flushes on motocross bikes. Replace the drain bolt (consider a new crush washer if the original is damaged). Tighten to manufacturer specification. -
Refill With Fresh Coolant
Pour new coolant into the radiator filler neck. On the MC 85, watch for the small bleeder screw on the cylinder head. Loosen this screw as you fill to allow trapped air to escape. Continue filling until coolant appears at the bleeder screw, then tighten it back up.
Fill until the coolant is just below the filler neck rim with the bike upright. -
Check for Leaks & Bleed the System
Reinstall the radiator cap and covers. Start the engine briefly and let it idle with the bike upright. Allow minor revs to help circulate fluid. Shut off the engine and check for coolant level drop or any leaks. Top off as necessary.
Important Notes for 2025 GAS GAS MC 85 Owners
- Bleeder Screw Placement: The MC 85 uses a small bleeder port at the cylinder head – ensure all air is removed during refill. Failing to bleed air properly can result in engine overheating.
- Coolant Type: Always use a silicate-free, motorcycle-specific coolant with antifreeze properties, and never mix types. The MC 85 cooling system is aluminum-based – incompatible coolants can cause corrosion and premature wear.
- Maintenance Interval: Especially if you ride in mud, deep sand, or race, inspect and change coolant at least annually. Cloudy, rusty, or low coolant requires immediate servicing.
- Environmental Safety: Collect spent coolant for hazardous waste disposal. Do not dump it or wash it into ground drains.
Extra Model-Specific Tips
- Double-check hose and clamp tightness after any coolant service on the MC 85 – vibration and hard landings can loosen connections.
- If you notice overheating or frequent top-ups, inspect for radiator fin damage or leaks, which are common in competitive riding.
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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.