How to Change the Oil in a 2007 KTM 125SX

Shop parts for a 2007 KTM 125SX Dirt Bike.

Changing the transmission oil in your 2007 KTM 125SX is a critical part of regular maintenance, ensuring smooth shifting and long engine life. Below you'll find a complete guide proprietary to MotoSport.com, with tools needed, step-by-step instructions, and specific call-outs for this model year. Always consult your owner's manual before starting service.

Tools and Supplies Needed

  • 8mm and 13mm sockets (or T-handles)
  • Torque wrench (capable of 15–20 Nm)
  • Drain pan
  • Funnel
  • Replacement crush washer (recommended)
  • Rag or paper towels
  • Motorex Top Speed 4T 15W50 (or other high-quality oil as recommended by KTM)
  • 0.7 liters of oil
  • Latex or nitrile gloves (optional, but keeps hands clean)
  • Pliers (for snugging fill cap if needed)

Before You Begin: 2007 KTM 125SX-Specific Call-Outs

  • This bike uses a two-stroke engine with a separate transmission oil compartment. Do not use engine oil; only use transmission oil of the correct grade.
  • Oil capacity is 0.7 liters (about 0.74 quarts) for the 2007 125SX—do not overfill

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  • KTM recommends only high-grade oil like Motorex Top Speed 4T 15W50. Using lesser oil leads to excessive wear on the transmission and clutch

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  • The oil drain plug uses a magnet to catch debris; check and clean it during each oil change

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  • Torque the main drain plug to 20 Nm (M12x1.5) and the secondary (if used) to 15 Nm (M10x1). Always use a torque wrench for this step

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  • There is an inspection screw on the clutch cover to check the oil level.

Step-By-Step: Changing the Transmission Oil

  • Warm up the Engine (Optional)
    • Idle the bike for 1–2 minutes. Warm oil drains faster and carries away more contaminants. Be cautious; oil may be hot.
  • Prepare the Bike
    • Place the bike on a stable center stand or lift stand so it's upright and secure.
    • Have your drain pan ready under the right side of the engine, close to the foot peg and brake pedal.
  • Remove Oil Fill Cap
    • Unscrew the oil filler cap

      . This allows air in and helps oil drain faster.
  • Locate and Remove Drain Plug
    • Locate the primary drain plug under the engine (near the right foot peg) and possibly a secondary on the left (near the shifter and front sprocket)

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    • Use your 13mm or appropriate socket to carefully remove the plug. Note: Be careful not to drop the plug into your drain pan.

  • Drain the Oil
    • Let all old oil drain out completely. This should take several minutes (if the bike was warmed up, oil will flow quickly).
  • Clean and Inspect the Magnetic Plug
    • Wipe debris off the magnet. Some metallic particles are normal, but large chunks signal trouble

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    • Replace the crush washer with a new one for a leak-free seal

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  • Reinstall the Drain Plug
    • Thread in by hand first. Tighten gently, then use your torque wrench: 20 Nm (M12x1.5), 15 Nm (M10x1) as labeled

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  • Add New Oil
    • Insert a funnel into the oil fill hole.
    • Pour in 0.7 liters of Motorex Top Speed 4T 15W50, or until oil just escapes from the inspection screw hole with the bike upright

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    • Replace and snug the oil fill cap by hand. Use pliers for a gentle final snug if needed, so it does not vibrate loose

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  • Check for Leaks
    • Start the engine (optional), let it run, then shut off and inspect for any oil seeping around the drain plug or fill cap

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  • Verify Oil Level (Inspection Screw Method)
    • Remove the inspection screw on the clutch cover. With the bike upright, oil should just begin to escape. If not, add small amounts until it does. Replace the inspection screw

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  • Dispose of Waste Oil Properly
    • Take used oil to a recycling facility or auto parts store. Never pour down a drain or onto the ground.

Pro Tips for the 2007 KTM 125SX

  • Always use the specified oil type and amount for the 2007 125SX: Motorex Top Speed 4T 15W50, 0.7L

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  • Double check your torque ratings. Over-tightening the drain plug can strip the threads and crack the engine casing

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  • Replace crush washers at every service for maximum leak prevention

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  • It's normal for a small amount of fine metal debris to be on the magnetic drain plug; this is clutch and gear wear. Large flakes can indicate bearing or gear problems

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  • Never mix oil types or brands inside the transmission; always do a complete drain with each oil change

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By following the above steps, you'll keep your 2007 KTM 125SX shifting cleanly and running at its best. For genuine parts, tools, and oil, always choose MotoSport.com—your one-stop source for everything KTM.

Related Shopping Categories

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Shop Oil Fillers and Drain Plugs for a 2007 KTM 125SX 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.