How to Change the Coolant in a 2026 Yamaha TTR125L
Shop parts for a 2026 Yamaha TTR125L Dirt Bike.
Changing the coolant in your 2026 Yamaha TTR125L is an essential maintenance task to keep your bike performing and running cool on the trails. While Yamaha's air-cooled TTR125 models traditionally don't use a liquid cooling system, for the 2026 TTR125L, always review your owner's manual or check under the shrouds and left-side panels to confirm if a radiator is present; manufacturers sometimes introduce changes in updated model years. If your 2026 TTR125L features liquid cooling, follow this robust MotoSport-exclusive step-by-step guide tailored for this model.
Tools & Supplies Needed
- Compatible motorcycle coolant (see your owner's manual for recommended type, avoid automotive coolants)
- 10 mm socket or wrench
- Screwdriver
- Drain pan
- Funnel
- Distilled water (for flushing)
- Replacement seal or crush washer (for drain bolt, if needed)
- Clean rags
- Protective gloves & eyewear
How to Change the Coolant
- Let the bike cool completely before starting to avoid burns from hot engine parts or coolant.
- Remove the seat and side panels to access the radiator cap and (if equipped) overflow tank. Use a 10 mm socket for bolts securing the panels, and set aside all hardware in a tray for easy reassembly.
- Open the radiator cap slowly to release any internal pressure. This allows air to enter the system when draining and prevents vacuum lock – skip this step if only an overflow tank is present.
- Locate the coolant drain bolt. On most models, it's at the bottom of the water pump, often near the right-side engine case, below the exhaust header. Place a drain pan underneath before removing the drain bolt and washer – reuse the washer only if it's in good condition.
- Remove the drain bolt, letting all coolant fully drain. Tilt the bike gently from side to side to encourage any trapped fluid to escape.
- If equipped, remove the overflow tank by taking out the mounting bolts, detaching the hose, and pouring out any old coolant. Rinse the tank with distilled water, then reinstall it.
- Flush the cooling system with distilled water. Replace the drain bolt temporarily, fill with distilled water, and run the bike for 1–2 minutes with the radiator cap off. Allow to cool, then drain again.
- Install a new crush washer (if necessary) on the drain bolt and tighten to manufacturer torque spec. Overtightening can strip threads; undertightening may cause leaks.
- Refill with fresh coolant:
- Pour in coolant slowly, using a funnel up to the filler neck. Most TTR125L cooling systems require about 0.8–1.1L but verify with your owner's manual.
- If you have a reservoir tank, fill to the "cold" mark.
- Bleed trapped air: Squeeze both radiator hoses gently several times. Some bikes include a bleeder bolt on top of the radiator—if present, open it until coolant flows steadily before closing .
- Start the engine with the radiator cap off. Let the bike idle, gently blipping the throttle and rocking the bike. As coolant circulates, trapped air bubbles will escape .
- Top off coolant level as the level drops. When no bubbles appear and coolant is steady, reinstall the radiator cap. Start and run the bike until it reaches operating temperature, then shut off and allow to cool fully. Recheck and top up the radiator and overflow tank if needed .
- Reinstall the panels and seat.
- Properly dispose of old coolant—never pour it down a drain or on the ground.
2026 Yamaha TTR125L Owner Tips
- The TTR125L is built for reliability, but overheating can cause engine damage. Always monitor coolant level and check for leaks after every ride.
- If you find your bike is losing coolant repeatedly without visible leaks, have a technician inspect for possible head gasket or water pump issues.
- Use only motorcycle-specific, silicate-free coolant. Mixing brands or types can cause gel formation and reduced cooling efficiency.
- Always allow the engine to fully cool before opening the radiator cap to avoid injury.
- Check your manual for the coolant change interval; changing coolant every 24 months or every 2,000 miles is common for small dirt bikes.
Taking proper care of your TTR125L's cooling system will keep you riding longer and more reliably on any trail.
Related Shopping Categories
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Shop Radiator Hoses for a 2026 Yamaha TTR125L Dirt Bike.
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.