How to change the coolant in a 1995 KTM 125EXC Dirt Bike

How to Change the Coolant in a 1995 KTM 125EXC: Step-by-Step Maintenance Guide

Shop parts for a 1995 KTM 125EXC Dirt Bike.

Maintaining your 1995 KTM 125EXC with routine coolant changes ensures optimal engine performance, longevity, and reliability on trails and tracks alike. This exclusive MotoSport guide walks you through changing the coolant, while highlighting important details unique to the 125EXC model of this era.

What You Will Need

• New coolant meeting or exceeding manufacturer specifications
• Drain pan or container
• 8 mm socket or wrench
• Funnel
• Shop rags
• Optional: compressed air for additional flushing

Preparation – Safety First

• Ensure the engine is completely cool before starting. Hot coolant can cause burns.
• Work in a well-ventilated area to avoid inhaling fumes.

1. Access the Radiator Cap

Remove the seat and any body panels obstructing access to the radiator. Twist the radiator cap counterclockwise and set it aside.
On the 1995 KTM 125EXC, the radiator cap is easily accessible with minimal disassembly, but always confirm your specific configuration.

2. Drain the Old Coolant

• With the bike upright, find the water pump drain bolt - this is typically an 8 mm bolt located at the lowest point of the water pump cover.
• Place your drain pan beneath the water pump area.
• Carefully remove the drain bolt and allow all coolant to flow out completely. Opening the radiator cap before this step will speed up draining.
• Inspect the coolant for debris or discoloration, which may indicate cooling system issues.

3. Flush the Cooling System (Highly Recommended)

If your coolant is especially contaminated or you are changing coolant types, flush the system with distilled water or use compressed air for a more thorough clean-out. Remove both lower and upper radiator hoses if needed, and blow air through to clear any remaining old coolant.

4. Reinstall Drain Bolt

Once the coolant is fully drained and the system flushed, reinstall the water pump drain bolt securely. Ensure the sealing washer is in good condition to avoid leaks.

5. Refill with Fresh Coolant

• Position the bike upright on level ground.
• Slowly pour new coolant into the radiator using a funnel. Fill until the radiator is completely topped off and coolant is visible at the neck. For the KTM 125EXC, overfilling can lead to overflow during operation, so fill only to the base of the neck.

6. Bleed & Check for Air Pockets

With the radiator cap off, gently rock the bike side-to-side to help trapped air escape. You can also squeeze radiator hoses by hand to expel bubbles.

7. Finalize

• Reinstall the radiator cap and any previously removed bodywork.
• Start the engine and let it idle for several minutes, then shut it off and recheck the coolant level once the bike cools again. Top off if necessary.
• Inspect for leaks around the drain bolt and hose connections.

Noteworthy Tips for 1995 KTM 125EXC Owners

• The 1995 125EXC uses a two-stroke engine that relies on a well-maintained cooling system for maximum power and durability. Avoid using plain water; always use high-quality coolant for corrosion protection and proper operating temperatures.
• Always monitor for cracked hoses or brittle rubber at this age – original hoses may need replacement after decades of use.
• If you notice consistent coolant loss or overheating, check your radiator cap and water pump seals as these are wear items known to age out on 1990s dirt bikes.
• Refer to manufacturer recommendations for coolant type and capacity. The owner's manual provides essential information for this model.

Regular coolant changes are a key part of long-term maintenance for your classic KTM. Tackle the process step by step, and you will keep your 125EXC running cool and strong, season after 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.