How to Change the Coolant in a 2021 GAS GAS EX 300
Routine coolant changes are crucial for maintaining the performance and longevity of your 2021 GAS GAS EX 300. Follow this comprehensive MotoSport guide for a safe and effective coolant service specific to this two-stroke enduro model. Always allow the bike to cool completely before opening any part of the cooling system—hot coolant can cause severe burns.
Essential Tools and Supplies
- Phillips screwdriver or 8mm socket (radiator shroud removal, if needed)
- Drain pan
- Correct premixed coolant for aluminum engines
- Funnel
- Torx or allen wrench (for radiator drain bolt)
- Protective gloves and eye protection
- Clean towels/rags
Step-by-Step Coolant Change Procedure
- Ensure safety first.
- Let the engine cool completely before opening the radiator cap.
- Access the cooling system.
- Place the bike upright on a stand.
- If necessary, remove the radiator shrouds for easier access to the radiator cap and drain bolt.
- Remove the radiator cap.
- Press down and rotate the radiator cap counterclockwise. Only remove the cap when the system is cool–never when hot.
- Find and remove the coolant drain bolt.
- The main drain bolt is located at the lower water pump cover on the right side of the engine. Place your drain pan underneath the area.
- Loosen and remove the bolt from the water pump cover, allowing all coolant to drain completely. You may also gently tilt the bike left and right to ensure all old fluid escapes.
- Flush if needed.
- If the coolant is exceptionally dirty or contaminated, you can flush the system using distilled water. Replace the drain bolt, fill the radiator with distilled water, run the engine briefly, and repeat the drain process.
- Reinstall the drain bolt.
- Replace and tighten the drain bolt securely after verifying the sealing washer or o-ring is in good condition.
- Refill the radiator.
- Pour the new coolant into the radiator until it's nearly full. Use a long funnel for precision and to avoid spills. Fill to just below the filler neck.
- Bleed air from the system.
- Some engines, including the 2021 EX 300, may have a small bleeder screw on the cylinder head or on the top of the radiator. Loosen this screw slightly while filling coolant to release trapped air, then retighten when only fluid (no bubbles) emerges.
- Reinstall the radiator cap and test.
- With the fluid at the proper level and air bled, reinstall the radiator cap firmly.
- Start the engine and let it idle for a few minutes. Shut it down, let cool, then recheck the coolant level–top off as necessary.
- Inspect for leaks.
- Verify that the water pump cover and radiator hoses are free from leaks. Tighten as needed.
GAS GAS EX 300 Specific Tips
- The 2021 EX 300 uses a two-stroke powerplant with a high-performance aluminum engine–always select a coolant that is compatible with magnesium and aluminum cooling systems to avoid corrosion.
- This model may feature a small bleed screw on the coolant head for precise air removal, reducing the risk of airlocks that can lead to overheating.
- Inspect your radiator cap for any wear or loss of pressure–replace if needed, as even a minor seal leak can cause poor cooling efficiency.
- Coolant changes should be part of your seasonal maintenance, especially before races or when riding in extreme conditions for optimal engine protection.
Safe Disposal
- Used coolant is toxic and must be disposed of at an approved recycling center–never pour it down the drain or on the ground.
Performing regular coolant maintenance on your 2021 GAS GAS EX 300 keeps your engine running cool and reliable in all conditions. If you need genuine parts or high-performance coolant, Shop parts for your ride now!
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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.