How to Change the Oil in a 2008 Kawasaki KX100

Shop parts for a 2008 Kawasaki KX100 Dirt Bike.

Changing the oil in your 2008 Kawasaki KX100 is essential for keeping your two-stroke dirt bike running smoothly and extending the life of its transmission. Although this bike is a two-stroke and uses premix for top end lubrication, the oil change process actually replaces the transmission/gear oil, which is crucial for clutch and gear operation. Neglecting this maintenance will lead to poor shifting and eventual mechanical failure, so make it a regular part of your routine.

Tools and Supplies Needed

  • 14mm socket and ratchet for drain bolt
  • Drain pan
  • Measuring cup (at least 1 liter capacity, with milliliter markings)
  • Funnel
  • New transmission oil – SAE 10W-40 recommended (700 milliliters required)
  • Clean rag
  • Optional: fresh drain bolt crush washer or gasket
  • Latex or nitrile gloves
  • Bike stand (to keep the bike upright and stable)

Step-by-Step Instructions

  1. Warm Up the Engine (Optional but Recommended) Start the bike and let it idle for about one minute. Warm oil drains more easily, carrying away more contaminants.
    “Idle the bike for a minute to make the oil drain faster”.
  2. Stabilize the Bike Place your KX100 on a stand so it’s upright and stable. This ensures complete draining and accurate oil level checking later.
  3. Locate and Remove the Drain Bolt Find the drain bolt under the engine. On the KX100, it’s a 14mm bolt on the bottom of the right side case (often painted green from the factory).
    Use a 14mm socket with a ratchet to loosen and remove the bolt, taking care not to burn yourself if the engine was just run. Catch the old oil in your drain pan.
    KX100 Call-Out: There should be a crush washer under the bolt. If it’s missing or damaged, replace it to avoid leaks.
  4. Let Oil Drain Completely Allow the oil to drain until the flow drips to a stop. Wipe up any spillages with your rag.
  5. Reinstall the Drain Bolt Reinstall the drain bolt by hand, making sure the washer is in place. Snug it down gently with your 14mm socket – do not overtighten to prevent stripping the case threads.
    “Be careful not to snug this green bolt down too tight or you'll strip the threads”.
  6. Add New Oil Measure exactly 700 milliliters of high-quality 10W-40 transmission oil using your measuring cup.
    Insert the funnel into the oil fill hole (right side of the engine, above the clutch cover). Pour in the new oil slowly.
    “The KX 85 and the KX 100 both take 700 milliliters of oil”.
    KX100 Call-Out: Use a brand and grade of oil suitable for wet clutches (SAE 10W-40 is factory spec).
  7. Replace the Oil Fill Cap Once filled, securely replace the oil filler cap.
  8. Check Oil Level Remove the bike from the stand and hold it upright and level. There is a small oil-level check screw or sight notch in the case. Remove this plug; the oil should reach the notch – top off if necessary. If oil spills out, you may have slightly overfilled, which is not serious, but wipe away excess and reinstall the check plug.
    “Check the oil level after filling the bike with oil...there's a little notch in the case and the oil level should be equal with that”.
  9. Dispose of Used Oil Properly Pour the old oil into a sealed container and bring it to a recycling center or auto parts store. Never pour it out on the ground or in household drains.
  10. Start the Bike and Inspect for Leaks Run the bike for a minute, then check for any oil leaks at the drain bolt and fill cap. Tighten if necessary – but remember, do not overtighten.

2008 Kawasaki KX100 Specific Call-Outs

  • Always use SAE 10W-40 oil as per the owner’s manual. Inferior oil can damage the wet clutch or transmission parts.
  • The oil capacity is 700 milliliters – do not overfill.
  • Never overtighten the drain bolt. Aluminum threads are easy to strip and expensive to repair.
  • If the old oil is gray or metallic, monitor for excessive clutch or transmission wear and consider more frequent oil changes.
  • Check your manual’s maintenance schedule; change the oil at least every 10–15 hours of riding in normal conditions – more often for racing or muddy environments.

MotoSport.com Pro Tip

  • Consistency is key – use the same oil brand and spec for every change, and always log the date and hours in a maintenance record.
  • Keep a spare drain bolt washer in your toolbox; they easily get lost during changes.
  • Practice good shop safety – wear gloves, dispose of oil responsibly, and never work on a hot engine.

Conclusion

Changing the oil in the 2008 Kawasaki KX100 is a quick, user-friendly job that protects your bike’s most expensive parts. Set a reminder for regular oil changes and ride with confidence knowing MotoSport.com supports your passion for performance and reliability.

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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.