How to Change the Coolant in a 2020 KTM 150SX
Shop parts for a 2020 KTM 150SX Dirt Bike.
Regular coolant changes keep your 2020 KTM 150SX’s engine running cool & strong, whether you’re on the track or trail. The process is straightforward, but this high-revving two-stroke has some unique requirements every owner should know before you get started.
What You Need
- New premixed motorcycle coolant (silicate-free & ready to use)
- 8mm socket or wrench
- Drain pan
- Funnel
- Shop rags
- Torque wrench (recommended)
- Protective gloves
Step-by-Step Coolant Change for the 2020 KTM 150SX
- Let your engine cool. Allow the dirt bike to sit until the engine is completely cool. This prevents burns and avoids pressure in the cooling system.
- Remove the seat & shrouds if needed. For the 150SX, you can usually access the radiator cap and hoses directly. If not, quickly unbolt plastics for better access.
- Position the bike upright. Use a stand to level the motorcycle for accurate filling and draining .
- Remove the radiator cap. Twist and remove the radiator cap to release any pressure and allow air in for a faster drain .
- Place a drain pan under the water pump. Locate the coolant drain bolt (typically on the water pump cover on the right side of the engine). Use your 8mm socket to loosen it. Let the old coolant drain fully.
- Inspect the drain bolt’s O-ring. Make sure the sealing washer or O-ring is not damaged. Replace it if needed.
- Reinstall and torque the drain bolt. Clean, then reinstall the drain bolt and torque it to the manufacturer’s spec (usually around 15 Nm for this model) .
- Fill with new coolant. With the radiator cap off, slowly pour in the premixed coolant using a funnel until it’s flush with the bottom of the radiator neck. For the 2020 KTM 150SX, the system capacity is about 1.2 L (1.3 qt) .
- Bleed the air. With the KTM 2-strokes, trapped air may prevent proper cooling. As you fill, gently squeeze the radiator hoses to help purge air bubbles.
- Run the engine briefly. Reinstall the radiator cap, start the engine, and let it idle until warm. Turn it off, allow it to cool, then recheck the coolant level–add more if needed .
- Check for leaks. Inspect the drain bolt and hoses for any leaks, plus make sure the radiator cap seats tightly.
KTM 150SX-Specific Notes
- Always use coolants safe for aluminum engines–avoid car or tap water-based formulas, as they can cause corrosion.
- This model’s high-rpm engine and small radiators mean overheats can happen quickly if coolant is low or air remains in the system.
- Periodically inspect hoses and the radiator for damage after muddy rides or falls, since the 150SX is often raced hard.
- Don’t skip bleeding–air pockets are a common cause of overheating on recently serviced KTM 2-strokes.
When to Change Your Coolant
- Once a year or every 30 hours of engine time is typical for the KTM 150SX.
- Change sooner if the coolant appears dirty, rusty, or if the bike has overheated.
Changing the coolant on your 2020 KTM 150SX is quick insurance so every ride ends at the finish, not in the pits. Keep your cooling system dialed—your two-stroke will reward you with dependable performance all season long.
Related Shopping Categories
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Shop Radiator Hoses for a 2020 KTM 150SX 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.