How to Change the Oil in a 2011 Kawasaki KX100 — A MotoSport.com Guide

Shop parts for a 2011 Kawasaki KX100 Dirt Bike.

Changing the oil in your 2011 Kawasaki KX100 is an essential routine for keeping your two-stroke dirt bike running strong and shifting smoothly. While the oil in these bikes acts as transmission oil rather than as lubricating oil for the motor itself, keeping it clean and fresh is crucial for long gear life and smooth operation. In this guide, MotoSport.com walks you through the full process, including all tools needed, special tips specific to the KX100, and everything you need to know to keep your bike in race-ready shape.

Tools & Supplies Needed

  • 14mm socket or wrench (for oil drain bolt)
  • Socket wrench
  • Measuring cup (metric, 700 ml capacity)
  • Funnel
  • Drain pan or container for used oil
  • Clean shop rag or paper towels
  • New oil (Kawasaki recommends 10W-40 or similar high-quality transmission oil for two-stroke bikes—refer to your owner’s manual for brand and spec if unsure)
  • Replacement crush washer for drain bolt (recommended, optional but wise to have)
  • Gloves (optional, for mess-free hands)

Preparation

  • Warm up the bike. Start and idle the KX100 for a minute to let oil warm up. Warm oil will drain more efficiently, removing more contaminants from inside the gearbox. Never rev or ride the bike indoors, just a gentle idle is enough.
    “IDLE THE BIKE FOR A MINUTE TO MAKE THE OIL DRAIN FASTER”
  • Stabilize the bike. Put your bike on a stand so it sits upright and stable.
  • Power off the engine before you begin any work.

Drain the Old Oil

  • Locate the oil drain bolt. On the KX100, it’s a green bolt on the lower left side of the engine case, typically 14mm in size.
  • Place your drain pan beneath the bolt to catch all used oil.
  • Carefully remove the drain bolt with your 14mm socket. Be ready; oil flows out quickly and can be hot.
  • Remove the old crush washer (if present). It’s wise to replace this with a new one to prevent leaks during reassembly.
  • Let the oil fully drain. Tip the bike slightly if necessary to get every last drop. Give it a few minutes until it slows to drips.
“LOOSEN DRAIN PLUG AND REMOVE TO DRAIN OIL”

Reinstall the Drain Bolt

  • Inspect the drain bolt threads for wear or stripping. If damaged, replace it.
  • Install a new crush washer (recommended).
  • Hand-thread the bolt to prevent cross-threading. Tighten with your 14mm socket just until snug. Don’t overtighten—you could strip the case threads.
    “be careful not to snug this green bolt down too tight or you'll strip the threads”

Add Fresh Oil

  • Check the oil fill plug. Right side of the engine, typically at the top of the clutch cover.
  • Measure out 700 ml of fresh, quality transmission oil.
  • Use your funnel to pour oil in slowly, avoiding spills.
  • Replace the oil fill cap securely.
the kx 85 and the kx 100 both take 700 milliliters of oil

Check the Oil Level

  • Stand the bike upright so it’s perfectly perpendicular to the ground (off the stand, held upright).
  • Locate the oil check notch on the back side of the engine case, visible behind the fill plug area.
  • The oil should sit right at the bottom edge of this notch. Adjust as needed—do not overfill.
the oil level should be equal with that notch in the case

Final Steps

  • Wipe down any spills, and dispose of old oil responsibly.
  • Start the KX100, idle for a minute, and check under the bike for leaks.
  • Double-check level after the first ride and top off if needed.

Important KX100-Specific Notes

  • Don’t overtighten the green drain bolt—the KX100’s aluminum threads can easily strip, leading to major repairs.
  • Always use only 700 ml of oil. Overfilling causes clutch issues, while underfilling harms transmission parts.
  • If your old oil looks unusually gray or milky, it could indicate water contamination or worn internal parts—fix problems before running the bike hard.
  • The KX100 uses transmission oil only, since the combustion side is lubricated by premix in the fuel. Do not be alarmed that “engine oil” is not required as in a four-stroke.

Conclusion

With the right tools and careful attention to detail, you can quickly and easily change the oil on your 2011 Kawasaki KX100 and keep it performing at its best on the track or trail. For more OEM parts, recommended oils, and exclusive deals, trust MotoSport.com—your source for everything dirt bike.

Related Shopping Categories

Shop Motor Oil for a 2011 Kawasaki KX100 Dirt Bike.

Shop Oil Filters for a 2011 Kawasaki KX100 Dirt Bike.

Shop Oil Drain Pans for a 2011 Kawasaki KX100 Dirt Bike.

Shop Tools for a 2011 Kawasaki KX100 Dirt Bike.

Shop Oil Fillers and Drain Plugs for a 2011 Kawasaki KX100 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.