How to Change the Oil in a 2022 KTM 125 SX: MotoSport.com Exclusive Guide
Shop parts for a 2022 KTM 125SX Dirt Bike.
Keeping the transmission oil fresh in your 2022 KTM 125 SX is essential for optimal gearbox performance and longevity. This model, being a two-stroke, primarily uses oil for its transmission and not engine lubrication, so the process is straightforward but requires attention to detail. Follow these detailed, step-by-step instructions to confidently change the transmission oil in your KTM 125 SX.
Tools & Supplies Needed
- Socket set/T-handle (for drain plug removal)
- Torque wrench (capable of 20 Nm/14.8 ft-lb)
- Drain pan
- Funnel
- Clean rags
- Fully synthetic transmission oil, API rated for two-strokes (recommended: 0.8 liters or 0.85 quarts)
- New crush washer/seal for the drain bolt
- Pliers (for oil fill cap snugging)
- Optional: Nitrile gloves (for cleanliness)
Step-by-Step Instructions
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Warm Up the Bike
- Briefly run your 125 SX for a few minutes to allow the oil to warm and thin. This helps it drain more completely. Be cautious: oil can be hot after running.
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Stabilize the Bike
- Position your bike on a stand so it sits upright and stable, ensuring safe access to both the drain and fill locations.
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Remove the Oil Fill Cap
- Loosen and remove the fill cap before draining. This step allows air in and helps the oil flow out smoothly. Set the cap aside somewhere clean. Never skip this step.
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Drain the Old Oil
- Place your drain pan beneath the drain bolt (located under the engine case).
- Using your socket or T-handle, remove the drain plug. Be careful not to drop the bolt into the oil pan.
- Let the oil drain completely. Tilting the bike slightly from side to side helps extract every last drop.
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Clean the Drain Bolt
- Inspect and thoroughly clean the magnetic drain plug. Small metal shavings on the magnet are normal for these transmissions.
- Replace the drain plug's crush washer or O-ring with a new one to prevent leaks.
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Reinstall the Drain Bolt
- Hand thread the plug back in to avoid cross-threading.
- Torque the drain plug to 20 Nm (14.8 ft-lb) as specified by KTM. Many 2022– KTM two-strokes have this spec printed on the case for convenience.
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Refill with New Oil
- Using a funnel, pour 0.8 liters (or 0.85 quarts) of the recommended synthetic transmission oil into the fill port.
- Go slow and be careful not to overfill. For a precise fill, you can add oil until you see it begin to “weep” from the check bolt (if equipped on your model) or simply measure carefully by volume. It's common for it to use nearly the full bottle.
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Reinstall the Fill Cap
- Screw the fill cap back on and snug it down using pliers, as KTM recommends this ensures it doesn't work itself loose during riding.
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Check for Leaks
- Wipe down any excess oil. Start the engine and let it run briefly, then turn it off and inspect both the drain plug and fill cap for leaks.
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Dispose of Used Oil Responsibly
- Take your used oil to a recycling center or motorcycle shop that accepts used oil. Never pour oil on the ground or down the drain.
Special Model-Specific Callouts: 2022 KTM 125 SX
- Oil Type: Use a fully synthetic oil designed specifically for two-stroke transmissions. Check your manual for preferred brands and API specifications.
- Oil Capacity: The engine uses 0.8 liters (0.85 quarts) for a full change. Unlike some other bikes, it's not necessary to use a full quart.
- Torque Spec: Always torque the drain bolt to 20 Nm (14.8 ft-lb)—using a torque wrench is highly recommended to avoid stripping threads or leaks.
- Drain Plug Magnet: Metal shavings on the plug magnet are normal for this model; excessive chunks may indicate gearbox wear needing inspection.
- Crush Washer: Always replace the crush washer with each oil change to ensure a proper seal and prevent leaks.
- Oil Level Check: Some 125 SX models have a side check or weep bolt for monitoring the fill level. Add oil until it just starts to “weep” out, then seal.
Expert Tips
- Keep records of your oil change intervals in a notebook or your phone for maintenance tracking.
- Use gloves to keep your hands clean and avoid prolonged contact with used oil.
- Keep extra crush washers on hand—these are inexpensive but critical for a leak-free job.
Changing the transmission oil on your 2022 KTM 125 SX is a straightforward, essential maintenance task that helps protect your gearbox and keep you riding with confidence. For the best performance and component longevity, always use quality products and follow these model-specific instructions every time.
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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.