How to Change the Oil in a 2020 Kawasaki KX100

Shop parts for a 2020 Kawasaki KX100 Dirt Bike.

Performing regular oil changes on your 2020 Kawasaki KX100 is the key to keeping your two-stroke dirt bike running smoothly and extending the life of the transmission and clutch components. This step-by-step guide is proprietary to MotoSport.com and covers all the tools, exact steps, and model-specific nuances you need to know for your oil change.

Tools and Supplies Needed

  • 14mm socket and ratchet or wrench (for the drain bolt)
  • Funnel
  • Measuring cup (capable of measuring up to 700ml)
  • Drain pan
  • Fresh transmission oil (use high-quality two-stroke gear oil or 10W-40; manufacturer recommends 700mL)
  • New crush washer (optional but recommended)
  • Clean rags
  • Latex or nitrile gloves
  • Bike stand (to keep the bike upright and level for filling and checking)

Model-Specific Call-Outs for the 2020 KX100

  • The KX100 shares its transmission and oil change procedure with the KX85; both models use 700ml of oil–do not overfill.
  • The drain bolt is a 14mm hex head, located at the bottom of the right side case–don’t overtighten during installation or the threads may strip.
  • Always double-check the oil level by ensuring it reaches the notch in the sight/fill port when the bike is upright and perpendicular to the ground.
  • Inspect the color of the drained oil–cloudy or grayish oil may indicate clutch fiber wear or, rarely, water ingress; if this is observed, investigate further before riding.

Step-by-Step Oil Change Process

  1. Warm Up the Engine
    • Start your bike and let it idle for about 1–2 minutes. This helps the oil drain more completely and suspends debris for better removal. Be sure to turn the engine off before you begin working.
  2. Position the Bike and Gather Tools
    • Place your KX100 securely on a stand so it’s upright. Have all your tools and supplies nearby.
  3. Remove the Drain Bolt
    • Locate the 14mm drain bolt on the underside of the engine’s right side case. Place a drain pan beneath this point.
    • Using your socket, carefully loosen and remove the bolt. Let all the oil drain into the pan. Note that a crush washer is fitted–replace it if worn or deformed.
  4. Inspect and Clean
    • Check the condition of the oil–metallic particles or milky color can signal issues.
    • Clean the drain bolt and the area around the opening with a rag.
    • If possible, inspect the crush washer and replace it if necessary.
  5. Replace the Drain Bolt
    • Reinstall the drain bolt with its washer. Do not overtighten–a snug fit is sufficient to prevent leaks (avoid stripping the threads which are relatively soft on this aluminum case).
  6. Refill with Oil
    • Measure out 700ml of fresh gear oil using your measuring cup–this is critical for the KX100, as overfilling can harm shifting and clutch performance.
    • Insert a funnel into the oil fill hole (located just above the clutch cover on the right side case) and slowly pour in the oil.
    • Replace the fill cap securely after adding the oil.
  7. Check the Oil Level
    • With the bike upright and level on the stand, open the fill port again and check inside. The oil should be level with the small notch in the case–this is your fill guide.
    • If it’s below the notch, add a small amount more; if above, blot out until it is level with the notch.
    • Wipe up any spills and reinstall the fill plug/cap.
  8. Dispose of Old Oil Properly
    • Pour the used oil into a sealed container and take it to a recycling center—never pour it onto the ground or drain.
  9. Final Checks
    • Start the bike again and let it idle for a minute. Check for any leaks at the drain plug or fill cap.
    • If everything checks out, you’re ready to ride.

Frequently Asked Questions About KX100 Oil Changes

  • What type of oil should I use? Always use a top-quality two-stroke transmission oil formulated for high-performance motocross bikes, or (if necessary) a recommended alternative like 10W-40 motorcycle oil.
  • How often should I change the oil? For racing or frequent riding, change your KX100’s oil every 3–5 hours or after every two to three motos. For casual use, every 10 engine hours is standard.
  • My oil looks gray or milky. What now? This can signal clutch fiber wear (normal in small amounts) or possible water contamination from a bad gasket or seal (less common). If unsure, consult your service manual or dealer before riding again.

MotoSport Pro Tips for KX100 Oil Changes

  • Always use a torque wrench if possible to reinstall the drain bolt. Aluminum threads in your case are easy to damage if overtightened.
  • If racing, always change your oil more frequently for best clutch and gearbox life.
  • Keep spare crush washers and a quart of oil on hand–you’ll use them often.
  • Log your oil changes in a maintenance notebook for reference and value retention in case you ever sell the bike.

Maintaining your 2020 Kawasaki KX100 with routine oil changes takes less than 15 minutes and will keep you shifting smoothly and riding confidently. For OEM and pro-level tools, supplies, and expert advice, trust MotoSport.com—your dirt bike authority.

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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.