How to Change the Coolant in a 2020 KTM 250SX
Shop parts for a 2020 KTM 250SX Dirt Bike.
Keeping your 2020 KTM 250SX running cool under pressure starts with a fresh coolant change. The right coolant and a precise process will help prevent overheating and protect valuable engine components. This model features a liquid-cooled two-stroke powerplant, so following the correct procedure is crucial for both performance and reliability. Below you will find a proprietary MotoSport guide, including tips unique to the 250SX for your best results.
What You Need
- Metric socket set (especially 8mm or 10mm)
- Drain pan
- Fresh coolant compatible with aluminum engines (silicate/phosphate-free)
- Funnel
- Clean rags
- Optional: Torque wrench for reinstalling bolts
Step-by-Step Coolant Change
- Start with a Cold Engine
Always work on a stone-cold engine to avoid burns and ensure safety. Place the bike securely on a stand, keeping it upright for accurate filling. - Remove the Radiator Cap
Slowly remove the radiator cap to relieve pressure—do this carefully to avoid splashing any remaining hot coolant. - Drain Old Coolant
Position a drain pan under the water pump on the right side of the engine.
Remove the water pump cover bolt (typically the lowest bolt), which acts as the drain. Allow all coolant to drain. If coolant comes out slowly, you can remove a radiator shroud bolt or gently wiggle the bike to help the flow. - Flush (Optional but Recommended)
Add a small amount of distilled water to the radiator, reinstall the drain bolt, run the bike briefly, and drain again to remove any debris or residues. Repeat as necessary until the drained fluid is clear. - Inspect the Coolant System
Check the condition of hoses, clamps, and the radiator cap. The 2020 KTM 250SX is prone to wear on radiator T-pipes and hose connections; inspect for cracks or leaks for maximum reliability. Replace components as needed. - Refit the Drain Bolt
Reinstall the water pump cover bolt securely. If you have a torque wrench, use manufacturer-recommended torque settings to avoid stripping threads. - Fill with New Coolant
Using a funnel, slowly add new coolant into the radiator until it reaches the base of the filler neck. KTM recommends a high-quality premixed coolant designed for aluminum radiators. Avoid mixing different coolant types. - Bleed the System
To prevent air pockets—a common cause of overheating on 250SX models—slowly rock the bike side to side and gently squeeze radiator hoses to release trapped air. Top off coolant as needed during this process. - Replace the Radiator Cap
Securely reinstall the radiator cap. Make sure it is locked in place—improperly fitted caps are a known cause of leaks and overheating. - Start the Bike and Recheck Level
Start the engine with the bike upright. Let it idle until it reaches operating temperature. After cooling, double-check the coolant level and add more if necessary.
Notes Specific to the 2020 KTM 250SX
- This model’s engine is sensitive to overheating. Always use a performance-grade coolant; cheaper options may not offer sufficient protection.
- Inspect radiator louvers and guards for blockages. MX riding often leads to mud and debris buildup—clear these before refilling.
- Factory radiator caps are 1.8 bar; consider upgrading if you ride in extreme conditions to reduce the chance of boil-over.
When to Change Coolant
- At least once per season, or every 40–50 hours of riding.
- If you notice discoloration, debris in the coolant, or overheating signs.
- After any engine overheating event.
Changing the coolant following these steps will help maximize performance and preserve your 2020 KTM 250SX for the long haul. Stay on top of maintenance for the ride you love, and remember—MotoSport has your back for the parts and products you need.
Related Shopping Categories
Shop Radiators for a 2020 KTM 250SX Dirt Bike.
Shop Coolant for a 2020 KTM 250SX Dirt Bike.
Shop Temperature Sensors for a 2020 KTM 250SX Dirt Bike.
Shop Tools for a 2020 KTM 250SX Dirt Bike.
Shop Radiator Hoses for a 2020 KTM 250SX 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.