How to Change the Coolant in a 2015 GAS GAS TXT PRO 125: Step-by-Step Guide
Changing the coolant is an essential maintenance task that keeps your 2015 GAS GAS TXT PRO 125 running cool and performing at its best on the trials course. Follow this MotoSport.com proprietary guide designed specifically for your model–with a few TXT PRO 125 details you need to know.
Before You Begin: TXT PRO 125 Notes
- Always let the engine cool fully to avoid scalding when opening the radiator cap or draining the coolant.
- Your TXT PRO 125 uses a lightweight alloy engine, so always choose premium, aluminum-compatible motorcycle coolant–never use plain water or automotive coolant not formulated for motorcycles.
- Check the recommended coolant interval in your maintenance log; every two years is typical unless you ride in extreme conditions.
Tools & Supplies
- New, motorcycle-specific coolant compatible with lightweight alloy engines
- Drain pan
- Socket set and Allen keys
- Rags and some distilled water (optional for flushing)
- Replacement drain bolt washer (recommended)
Coolant Change Procedure
- Prep the Motorcycle
Ensure your TXT PRO 125 is on a level stand. Remove the seat and fuel tank to access the radiator. Close the fuel tap and detach the fuel hose from the tank. Use a 4mm Allen wrench to remove the tank’s front upper retaining screw. Carefully lift the tank off the bike.
Tip: Inspect fuel lines and connections for wear while it’s apart. - Drain the Old Coolant
Place a drain pan beneath the water pump area. Locate the coolant drain bolt on the lower left-hand side of the engine or at the base of the water pump. Carefully remove the bolt. Open the radiator cap to allow the system to vent and speed drainage. Allow all coolant to drain completely.
Never remove the radiator cap when the engine is hot. - Flush the Cooling System (Optional, but Recommended)
If your coolant is especially dirty or you’ve never changed it, pour distilled water through the radiator until it runs clear from the drain. For stubborn deposits, a 50/50 mix of distilled vinegar and water can be used, cycling through the engine briefly (with cap on) before flushing thoroughly again with clean distilled water.
Replace and securely tighten the drain bolt with a new washer to prevent leaks. - Add Fresh Coolant
With the drain bolt secure, fill the radiator slowly with your chosen coolant up to the base of the filler neck. Tilt the bike gently left and right–this helps air bubbles escape from the system. Once topped up, temporarily fit the radiator cap. - Bleed the System
Start the engine and let it idle with the radiator cap off. Watch for air bubbles escaping at the fill neck. When the coolant flows steady with no bubbles, top up as needed and replace the cap.
Check the manual for the official coolant capacity and never overfill. - Reassemble and Check
Reinstall the fuel tank and reconnect the hoses and fastenings in reverse order. Start the engine and let it warm fully–inspect for leaks at all connections. After cooling, recheck your coolant level and top up if necessary.
Special Advice for 2015 GAS GAS TXT PRO 125 Owners
- This model features a robust yet lightweight cylinder head and radiator assembly; corrosion or scale from improper coolant can cause overheating and head gasket issues–always use quality coolant and flush thoroughly when changing.
- Periodically check for coolant loss around water pump seals and radiator; the off-road environment can accelerate wear.
- If riding in extreme cold, confirm your coolant is rated for at least -30°C to prevent freezing damage.
Regular coolant changes will help your TXT PRO 125 stay at peak performance, avoid costly overheating failures, and enjoy flawless trial rides. Have all your OEM and upgrade parts ready–and remember to Shop parts for your ride now!
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.