How to Change the Coolant in a 2021 GAS GAS TXT GP 125
Regular coolant maintenance on your 2021 GAS GAS TXT GP 125 is essential for peak thermal performance, component longevity, and optimal ride conditions, whether you're training or competing. Below, MotoSport provides a step-by-step proprietary guide to the coolant change process – tailored specifically for the TXT GP 125’s engineering and features.
What Owners Need to Know About the TXT GP 125 Cooling System
The 2021 TXT GP 125 uses a closed liquid cooling system designed for the high-demands of modern trials. Coolant should be changed periodically (at least annually or as specified by your service schedule) to prevent internal corrosion and overheating. Use only high-performance motorcycle-specific coolant – never plain water – to ensure ideal protection and performance. Always work with the engine completely cold to avoid burns or injury*.
Tools & Supplies Needed
- Fresh motorcycle coolant suitable for aluminum engines
- Metric sockets/wrench set (notably 6mm and 10mm)
- Catch pan for old coolant
- Clean rags
- Optional: funnel and compressed air
Step-by-Step Coolant Change Process
-
Preparation
Ensure the bike is upright on stable ground. Let the engine cool completely. Remove the seat and fuel tank for best access to the radiator and cap. -
Remove the Radiator Cap
Slowly open the radiator cap to release any residual system pressure. Place the cap aside so debris doesn’t contaminate the system. -
Locate & Remove the Coolant Drain Bolt
Find the drain screw in the water pump cover at the lower right side of the engine. Position your catch pan directly beneath. Remove the drain bolt and sealing washer, allowing old coolant to flow out completely. Inspect the washer; replace if damaged or crushed. -
Completely Drain the System
To ensure thorough draining, you can gently lean the bike side to side or remove the lowest radiator hose (if accessible). Let the system drain until it’s fully emptied. -
Reinstall the Drain Bolt
Clean the threads and seal area. Reinstall the drain bolt with a new washer if needed, tightening to 10 Nm (7.4 lbf ft) for a proper seal. -
Refill the Coolant
Using a funnel, slowly pour fresh coolant into the radiator until full. On the TXT GP, fill up to the bottom edge of the radiator filler neck for proper level**. -
Bleed Air from the System
Air pockets can compromise cooling. On the TXT GP 125, open the small bleeder screw at the top of the cylinder head to allow trapped air to escape as you fill. Close this bleeder as soon as only coolant flows out. -
Check the Level and Reassemble
Top off the radiator again if the level drops after bleeding. Refit the radiator cap securely, reassemble the tank and seat, and wipe any coolant residue from surfaces. -
Start & Check for Leaks
With the bike upright, briefly start the engine and let it idle (cap on, never run without coolant or with the cap off). Shut down and recheck the coolant level, topping up if needed. Inspect all drain and fill points for leaks.
Special TXT GP 125 Owner Tips
- The TXT GP 125 features a compact radiator and precise coolant passages; never overfill, as excess pressure can damage seals or hoses.
- Monitor the sight port and bleeder screw for proper coolant flow after service for the next few rides.
- Dispose of old coolant responsibly as it is toxic to animals and the environment.
*Always reference your owner’s manual for the most current safety and service recommendations for your TXT GP 125.
**Never mix coolant types; always flush with distilled water if switching brands or types.
Related Shopping Categories
Shop Radiator Hoses for Your Ride
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.