How to Change the Oil in a 2021 Kawasaki KLX140G: A Complete Guide for MotoSport.com

Shop parts for a 2021 Kawasaki KLX140G Dirt Bike.

Regular oil changes are key to keeping your 2021 Kawasaki KLX140G running its best whether tearing up the trails or cruising the back forty. This comprehensive guide, proprietary to MotoSport.com, will walk you step-by-step through the entire process, note the tools you’ll need, and highlight important model-specific tips for the KLX140G.

Tools and Supplies Needed

  • 17mm socket or wrench (for oil drain bolt)
  • 8mm socket and ratchet (for oil filter cover bolts)
  • Oil drain pan
  • New oil filter (Kawasaki OEM part #52010-1053 recommended)
  • New drain bolt washer/crush washer (Kawasaki #11061-0421)
  • 10W-40 motorcycle oil (fully synthetic or conventional, at least 1 quart/1 liter)
  • Clean rags or shop towels
  • Torque wrench (recommended for reassembly)
  • Gloves and optional safety glasses
  • Brake cleaner (optional, for cleaning up any spills)

Step-by-Step Instructions

  1. Warm Up the Engine
    • Run the engine for 1-2 minutes to warm up the oil. This ensures more complete drainage and helps suspend contaminants in the oil for removal. Shut the engine off and let it sit for a minute before proceeding.
      Note: Work in a well-ventilated area with the bike on a stand or level ground.
  2. Remove the Oil Fill Cap (Dipstick)
    • Unscrew and pull out the dipstick/fill cap located on the right side. Set it aside. This vents the crankcase and helps oil drain faster.
  3. Drain the Old Oil
    • Place your oil drain pan directly under the engine’s drain bolt (bottom left side of crankcase).
    • Use your 17mm socket or wrench to carefully remove the oil drain bolt and crush washer. Allow all oil to thoroughly drain.
      Kawasaki suggests inspecting the oil for metal shavings or unusual debris, which could indicate internal engine wear.
    • Replace the old crush washer with a new one; reusing old washers can cause leaks.
  4. Remove and Replace the Oil Filter
    • On the right-hand side of the engine, identify the small round oil filter cover secured with three 8mm bolts.
    • Use an 8mm socket and ratchet to loosen and remove all three bolts evenly. Be careful as some oil will drip out.
    • Carefully pull off the cover. Remove the old oil filter and take note of the orientation for the new filter.
    • Important for KLX140G owners:
      • There is a small O-ring on the oil filter cover–ensure this stays in place, is not cracked, and is reinstalled properly during reassembly. Without it, you can cause a leak or lose pressure.
      • Some early KLX140 models had two O-rings; the 2021 KLX140G uses one–always double-check against your parts.
    • Clean the filter cover and mating surfaces.
    • Insert the new oil filter in the same direction as the original; the closed end faces the engine.
    • Reinstall the cover, tighten the 8mm bolts evenly by hand first, then torque to manufacturer specs (typically 7.2 Nm/5.3 ft-lbs).
  5. Reinstall the Drain Bolt
    • Thread the drain bolt with the new washer back into place by hand to avoid cross-threading.
    • Tighten the drain bolt to manufacturer specs (usually 29 Nm/21 ft-lbs; check your service manual). Avoid over-tightening, which could strip threads.
  6. Refill with Fresh Oil
    • Pour in 0.95 quarts (approx. 900 mL)–the correct fill amount for the KLX140G. Avoid overfilling.
    • Screw the dipstick in gently, then remove it to check oil level. Add small amounts if needed to reach the top line.
  7. Start and Inspect
    • Reinstall the dipstick, start the engine, and let it idle for 30-60 seconds. Turn it off and check for any leaks from the drain bolt or filter cover.
    • Wait a minute, then check the oil level again. Top off if necessary.
    • Wipe up any oil residue and properly dispose of the used oil and filter at an approved recycling center.

KLX140G/2021 Model-Specific Call-outs

  • The KLX140G’s oil change is typical of most Kawasaki’s air-cooled 144cc single-cylinder engines from 2017–2021. The process is shared with other KLX140 models but double-check torque and oil specs for the “G” variant.
  • Always use a new drain/crush washer on reinstallation to prevent slow leaks, a known issue if this is skipped.
  • The OEM oil filter is highly recommended; off-brand filters may not fit properly or lack the correct pressure relief.
  • Check the filter cover O-ring for damage—this is the primary source of post-oil-change leaks on this model.

Final Tips from MotoSport.com

  • Keep a maintenance log—note the type and amount of oil, date, and total hours/mileage at each oil change.
  • For harsh riding conditions (dust, mud, high heat), change oil more frequently than the manual suggests.
  • When in doubt, refer to your KLX140G owner’s or service manual for torque specs and oil recommendations.
  • Consider using nitrile gloves and have plenty of clean rags on hand for a tidy job.

Changing the oil on your 2021 Kawasaki KLX140G is simple, but crucial. With a bit of preparation and care, you’ll help ensure a long, strong life for your dirt bike—courtesy of MotoSport.com.

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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.