How to Change the Coolant in a 1999 KTM 250EXC – A MotoSport Guide
Shop parts for a 1999 KTM 250EXC Dirt Bike.
Changing the coolant on your 1999 KTM 250EXC is a straightforward maintenance task that keeps your two-stroke running cool and reliable. Follow these step-by-step instructions and be aware of model specifics to keep your legendary enduro bike in top condition.
What You Need
- Gloves & eye protection
- Drain pan
- Fresh motorcycle coolant (high-quality premix recommended, avoid automotive coolant)
- 10mm wrench or socket
- Funnel
- Rags for cleanup
Instructions: 1999 KTM 250EXC Coolant Change
-
Ensure your engine is cool.
Never open the radiator cap on a hot engine. Allow the bike to fully cool to avoid burns and releasing pressurized coolant. -
Remove the radiator cap.
Carefully open the radiator cap, ideally with a rag covering it to protect your hand from any residual pressure. Check for hissing and wait until it stops before removing the cap. -
Locate and remove the coolant drain bolt.
On the 1999 KTM 250EXC, the coolant drain bolt is at the water pump cover on the right side of the engine. Place your drain pan underneath, then use the 10mm wrench to remove the bolt and let the coolant drain completely. -
Flush with fresh water if needed.
If the coolant appears dirty, flush the system once or twice with distilled or deionised water, reinstalling the drain bolt finger-tight between flushes. Drain one final time before filling with new coolant. -
Reinstall the drain bolt.
Check the condition of the sealing washer. Replace if worn for leak prevention. Tighten the drain bolt securely (do not over-torque). -
Fill the radiator with fresh coolant.
Using your funnel, slowly pour in the new coolant until it reaches about 10mm above the radiator fins. Pouring slowly helps minimize trapped air. -
Bleed the cooling system of air.
Loosen (do not remove) the radiator bleeder screw (found on the top or side of one radiator) until coolant runs out without air bubbles, then retighten. This prevents air pockets that cause overheating. -
Check and top up the overflow tank (if equipped).
On some 250EXC models, check the level in the expansion/overflow tank and fill to the designated mark. -
Reinstall the radiator cap.
Ensure the cap is seated firmly. -
Run the engine and recheck levels.
Start the bike and let it idle, then gently rev to circulate coolant and release any remaining air. Shut it off, allow to cool fully, and top up the radiator if needed.
Essential Model Notes – 1999 KTM 250EXC
- Coolant capacity: The 1999 250EXC holds approximately 1 liter of coolant, but always check by visual level as capacities may vary slightly due to hose routing or updates.
- Bleeding is critical: This model does not have an automatic air purge. Always bleed air manually to prevent engine hot spots.
- Sealing washers can degrade: Always inspect and replace if needed, as leaks are common on older water pump covers.
- Radiator cap condition matters: Weak or old caps do not maintain pressure, causing boilover & overheating. Check yours annually.
- Use motorcycle-specific coolant: Many automotive coolants are silicate-based, which can cause water pump wear. Use silicate-free motorcycle coolant for optimal performance and system longevity.
Disposal and Safety
- Never pour old coolant on the ground – it is toxic to animals and the environment. Dispose responsibly at an approved recycling center.
- Keep coolant away from children & pets.
- Wear gloves, as contact with skin can be harmful.
Keep your 1999 KTM 250EXC running cool and ready for the trail by changing its coolant regularly. A little preventative care now means many more hours of riding with confidence – and remember, MotoSport has everything you need to keep your bike in peak condition.
Related Shopping Categories
Shop Radiators for a 1999 KTM 250EXC Dirt Bike.
Shop Coolant for a 1999 KTM 250EXC Dirt Bike.
Shop Temperature Sensors for a 1999 KTM 250EXC Dirt Bike.
Shop Tools for a 1999 KTM 250EXC Dirt Bike.
Shop Radiator Hoses for a 1999 KTM 250EXC 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.