How to Change the Coolant in a 2025 Sherco 125 SE FACTORY: Step-by-Step Guide

Shop parts for a 2025 Sherco 125 SE FACTORY Dirt Bike.

The 2025 Sherco 125 SE FACTORY is at the cutting edge of enduro technology, boasting an updated frame, lighter subframe, advanced airbox design, and numerous refinements for both performance & accessibility. Regular coolant changes are critical for protecting your high-revving 125cc two-stroke engine and ensuring optimal temperature management on the trail.

What Makes This Model Unique?

  • New frame for 2025 is lighter, with improved sealing on steering head bearings and revised geometry for better handling.
  • Updated side-access airbox for quicker maintenance and new placements for relays and battery, making routine service jobs a breeze.
  • 10-liter fuel tank for solid range during long enduro rides.
  • Lighter linkage and shock mounting system, reducing overall weight and simplifying some rear end tasks.

Tools & Supplies Needed

  • High-quality silicate-free coolant (suitable for aluminum engines)
  • Socket and ratchet set
  • Screwdrivers
  • Drain pan
  • Clean funnel
  • Shop towels or rags
  • Gloves and safety glasses

Step 1: Prepare Your Work Area

  • Allow the engine to cool completely before starting service–opening the radiator cap while hot can cause pressurized coolant to spray.
  • Secure the bike on a stand and remove the left side panel to access the radiator fill cap.

Step 2: Drain the Old Coolant

  • Locate the coolant drain bolt (commonly on the lower water pump cover) and the radiator cap.
  • Place your drain pan beneath the water pump.
  • Loosen the radiator cap to break any vacuum, then remove the drain bolt and let coolant flow out.
    Tip: For a thorough drain, gently tilt the bike side-to-side over the pan.

Step 3: Flush If Needed

  • If the old coolant is dirty or contaminated, refill with distilled water, run the bike briefly, and drain again. Repeat until water runs clear.
  • Reinstall the drain bolt and torque to spec (typically 10 Nm–confirm with your owner's documentation).

Step 4: Add New Coolant

  • With the drain bolt in place, pour high-quality coolant into the radiator via the fill neck using a funnel.
  • On this model, also remove the bleed screw if fitted (refer to your manual for precise location), pouring coolant until it flows from the bleed port without bubbles, then reinstall the screw securely.

Step 5: Bleed Air from the System

  • To ensure no air is trapped, gently rock the bike and squeeze both coolant hoses.
  • Top off the radiator until coolant reaches the base of the fill neck.
  • Reinstall the radiator cap and make sure it is secured tightly.

Step 6: Final Checks

  • Start the engine and let it idle for several minutes, monitoring temperature and inspecting for leaks.
  • Once fully cool, check the coolant level again (top off if necessary) and examine the drain bolt and hoses for seepage.
  • Reinstall the side panel.

Model-Specific Advice

  • Due to its compact frame and new plastics, accessing the radiator cap and drain bolt is faster than on older Sherco models.
  • The new airbox design and relocated battery/electronics mean less wiring obstructs coolant service steps.
  • Always use the correct coolant approved for modern magnesium-aluminum engine cases to prevent corrosion and gelling.

Staying on top of maintenance like coolant service helps your Sherco 125 SE FACTORY remain reliable and competitive throughout the riding season.

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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.