How to Change the Coolant in a 1997 KTM 125EXC

Shop parts for your ride now.

Routine coolant changes are critical to keeping your 1997 KTM 125EXC engine running cool and at peak performance. This guide, tailored specifically for your KTM EXC, will help you effortlessly perform a coolant change while noting a few model-specific tips that every owner should know.

Tools and Supplies You'll Need

  • Fresh coolant suitable for aluminum engines (silicate-free, premixed recommended)
  • A clean drain pan or bucket
  • Basic hand tools (socket set, screwdriver, pliers)
  • Funnel
  • Safety gear (gloves, eye protection)

Step-by-Step Coolant Change Procedure

  1. Prepare the Bike
    Ensure the engine is completely cool before starting any work—opening a hot cooling system can cause burns. Place the bike on a stand so it is upright and stable.
  2. Remove the Radiator Cap
    Locate the radiator cap at the top of the left radiator. Turn it counterclockwise and remove it to relieve any pressure and allow air in for complete draining – this is crucial for full fluid removal.
    Tip: Never remove the cap when the engine is hot.
  3. Drain the Old Coolant
    Position your drain pan under the right side of the engine, near the water pump cover. Locate the coolant drain bolt (referenced as #78 on KTM schematics) on the water pump cover. Remove the bolt and allow all coolant to fully drain into your pan.
    Some KTM EXC models may also allow you to remove the lower radiator hose to help the system drain faster.
  4. Inspect the System
    Check the color of your old coolant—milky or rusty appearance may indicate internal issues. Inspect the radiator, hoses, and water pump for any visible damage or leakage.
  5. Reinstall the Drain Bolt
    Clean and reinstall the coolant drain bolt securely. If fitted, replace the washer to prevent leaks.
  6. Refill with New Coolant
    Using a funnel, slowly add new coolant to the radiator until the level is visible at the base of the filler neck. Tap the radiator gently or squeeze the hoses to release any trapped air.
    For best protection, always use high-quality coolant made for aluminum components. Avoid regular green antifreeze unless specifically labeled safe for motorcycles and aluminum engines.
  7. Bleed the Air
    With the cap off, start the engine and let it idle for a minute—watch the coolant level drop as air escapes. Top off as necessary, then replace the radiator cap.
  8. Check for Leaks and Final Top-off
    Let the engine reach operating temperature and carefully check for leaks at the drain bolt and hoses. After shutdown and cool-down, re-check the coolant level and add more if necessary.

1997 KTM 125EXC Coolant System Tips

  • This model uses a simple, robust, dual-radiator cooling layout born from KTM’s enduro pedigree.
  • Inspect radiator cap rubber and ensure proper sealing—aging parts can cause pressure loss and overheating.
  • Avoid tap water—always use distilled water if you must mix with concentrate.
  • Check hose clamps and condition each change—original clamps can loosen over time, leading to hidden leaks after a refill.
  • If you ride in extreme conditions, increase inspection intervals and consider carrying spare hoses or zip ties on remote rides.
  • Always dispose of used coolant responsibly—never pour it down drains or on the ground.

Regular coolant changes ensure your KTM 125EXC stays cool and reliable, lap after lap and trail after trail. If you need any replacement radiators, hoses, caps or fresh coolant, MotoSport keeps a comprehensive stock for your 1997 KTM 125EXC.

Related Shopping Categories

Shop Radiators for a 1997 KTM 125EXC Dirt Bike.

Shop Coolant for a 1997 KTM 125EXC Dirt Bike.

Shop Temperature Sensors for a 1997 KTM 125EXC Dirt Bike.

Shop Tools for a 1997 KTM 125EXC Dirt Bike.

Shop Radiator Hoses for a 1997 KTM 125EXC 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.