How to Change the Coolant in a 2021 Sherco 125SE-R: Step-by-Step Guide
Shop parts for a 2021 Sherco 125SE-R Dirt Bike.
The Sherco 125SE-R is a precision-engineered two-stroke enduro machine built to deliver reliability and performance on and off the trail. Properly maintaining its cooling system is essential for engine longevity and consistent power delivery. Changing the coolant should be performed routinely or whenever the liquid appears contaminatedthis guide will show you how using best practices for this specific MMY dirt bike.
Important Safety Information
- Never remove the radiator cap when the engine is hot–hot coolant can cause severe burns and pressure release can be hazardous.
- Wear protective gloves and have eye protection handy, especially when handling coolant.
- Dispose of old coolant responsibly–use an approved collection center, never dump it on the ground.
- Only use coolant approved for high-performance motorcycles, such as Motul Motocool Factory Line (rated to at least -35°C).
Tools & Supplies Needed
- Gloves and rags
- Drain pan
- Flat blade screwdriver or socket set
- New, compatible coolant (approx. 1.1 liters required)
- Replacement bleed screw gasket (recommended)
Step 1: Preparation
- Ensure the bike is completely cool before starting.
- Set the Sherco 125SE-R on level ground using the stand. Make sure it's vertical for accurate fluid levels.
- Remove any plastics obstructing access to the radiator and expansion tank if necessary.
Step 2: Draining the Old Coolant
- Locate the radiator cap and remove it slowly to relieve any residual pressure.
- Position a drain pan under the water pump or the radiator drain bolt–typically found at the bottom of the engine side cover.
- Remove the drain bolt and allow all old coolant to flow out. Use caution as the coolant may still be warm or splash.
- Once drained, reinstall the drain bolt using a new gasket and torque to 8 Nm as specified.
Step 3: Filling with New Coolant
- Locate and remove the radiator bleed screw.
- Slowly pour new coolant into the radiator neck until it reaches the top and is visible within the core. The typical capacity is about 1.1 liters.
- Allow trapped air to escape through the removed bleed screw. Once coolant flows out steadily, reinstall and torque the bleed screw (use a new gasket if available).
Step 4: Bleeding the System
- Fill the radiator in stages, giving coolant time to work its way through the system and air bubbles to rise out.
- When coolant remains visible at the filler neck and at the expansion tank indicates "LEVEL," you are finished filling.
Step 5: Check & Top Off
- With the radiator cap still off, briefly start the engine and let it idle for a minute. This helps circulate coolant and release additional trapped air.
- Turn off the engine and once again check the rad core–add coolant if the level dropped.
- Reinstall and tighten the radiator cap.
Step 6: Inspect for Leaks & Final Steps
- Wipe any spilled coolant from the bike and engine parts.
- Inspect drain and bleed screws, as well as hoses, for any sign of leakage.
- After your first ride, let the bike cool and re-check the coolant level, topping off at the expansion tank if needed.
Special Notes for 2021 Sherco 125SE-R Owners
- This MMY uses a total of approximately 1.1 liters of coolant and requires careful air-bleeding due to its radiator design.
- Never substitute the recommended coolant with plain water or automotive antifreeze–always use motorcycle-specific, high-performance coolant to prevent overheating and corrosion.
- Always ensure the throttle cable play is correct after reassembly, as coolant servicing may require moving the tank or controls. Improper cable routing can cause inconsistent idling.
- Regular coolant checks are especially important if riding in mud, deep water, or extreme off-road conditions typical for this enduro model.
Related Shopping Categories
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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.