How to Change the Oil in a 2022 Yamaha YZ125

Shop parts for a 2022 Yamaha YZ125 Dirt Bike.

Changing the oil in your 2022 Yamaha YZ125 is a simple but crucial maintenance task to keep your dirt bike running smoothly. This step-by-step guide will walk you through everything you need to perform a proper oil change, including specific notes for this model. This process addresses the transmission (gear) oil, as the YZ125 is a 2-stroke and does not use engine oil in the same way as a 4-stroke.

Tools and Supplies Needed

  • Drain pan – To catch old oil
  • 12 mm socket or wrench – For the drain bolt
  • 4 mm Allen wrench – For the oil check bolt
  • Funnel – To make pouring oil easier
  • Measuring cup – To measure the exact amount of oil
  • Rag or shop towels – For cleaning up spills
  • Replacement crush washer (optional) – For the drain bolt if damaged or worn
  • Recommended oil: 10W-40 motorcycle transmission oil (Yamalube or equivalent, wet clutch compatible)

Specific Call-Outs for 2022 Yamaha YZ125

  • Recommended oil quantity is 0.69 US quarts (660 mL) of 10W-40 oil for the transmission.
  • Always let the bike idle for a few minutes before draining the oil. This allows the oil to flow out more thoroughly and carry with it debris and contaminants.
  • Ensure the bike is upright and on level ground during all steps, especially when checking oil level.
  • Use a new crush washer on the drain bolt for best sealing and protection against leaks.
  • Over-tightening the drain bolt can strip threads in the aluminum case—torque to factory specification: 14 ft-lb (19 Nm).
  • Always check the oil level using the oil check bolt on the side of the transmission case. Add oil until it just begins to seep out the check hole.

Step-by-Step Oil Change Instructions

  1. Warm up the Engine
    • Start the bike and let it idle for a few minutes to warm the oil. This helps it drain more completely.
    • Shut the engine off.
  2. Set Up Your Workspace
    • Stand the bike upright on a level surface or use a dirt bike stand.
    • Place the drain pan beneath the transmission drain bolt.
  3. Remove the Drain Bolt
    • Using a 12 mm socket, loosen and remove the drain bolt located underneath the crankcase.
    • Allow all the oil to drain completely—tilting the bike slightly side-to-side can encourage full drainage.
  4. Inspect and Replace the Drain Bolt Washer (if necessary)
    • Check the crush washer for flattening or damage; replace if worn or missing.
    • Clean the threads on the bolt and mating surface.
  5. Reinstall the Drain Bolt
    • Reinstall the crush washer, then thread the drain bolt in by hand.
    • Tighten with the 12 mm socket to 14 ft-lb (19 Nm)—do not over-tighten.
  6. Add New Transmission Oil
    • Remove the oil fill cap located at the top of the clutch cover.
    • Use a measuring cup to pour exactly 0.69 US quarts (660 mL) of 10W-40 oil into the fill hole. Use a long funnel to avoid spilling, especially since the exhaust header is nearby.
  7. Check Oil Level via Oil Check Bolt
    • Locate the oil check bolt on the side of the clutch cover (requires a 4 mm Allen wrench).
    • With the bike upright and level, remove the check bolt. If oil just begins to seep out, your level is correct. If not, add oil in small increments until it does.
    • Install and tighten the oil check bolt once done.
  8. Reinstall the Fill Cap
    • Screw the oil fill cap back on securely.
  9. Clean Up and Inspect
    • Wipe away any excess oil, especially near the drain bolt and fill/check areas.
    • Start the engine and check for leaks while idling for a minute.

Pro Tips for YZ125 Owners

  • Change the oil after every 5–10 hours of riding or after each race/riding session in muddy, sandy, or wet conditions to maximize gear life.
  • Discard old oil responsibly at a recycling center or auto parts store.
  • If you notice excessive metal shavings in the old oil, inspect your clutch and transmission for wear.
  • Log your oil changes in a maintenance record for optimal bike care and resale value.

Conclusion

Changing the transmission oil on your 2022 Yamaha YZ125 is straightforward and takes less than thirty minutes. Following these steps and the factory guidelines will ensure your YZ125 continues to deliver top performance on the track or trail.

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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.