How to Change the Oil in a 2024 Yamaha YZ125

Shop parts for a 2024 Yamaha YZ125 Dirt Bike.

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Tools and Materials Needed

  • Drain pan
  • 12mm socket/ratchet
  • 4mm Allen wrench
  • Funnel (preferably long to fit under exhaust)
  • Measuring cup (for precise oil volume)
  • Rag or shop towels
  • Replacement oil (10W-40 wet clutch compatible or as specified by owner’s manual)
  • New drain bolt washer/crush washer (recommended at each change)
  • Torque wrench (for correct drain bolt torque)

Model-Specific Notes for 2024 Yamaha YZ125

  • The YZ125 is a two-stroke: the engine oil is for the transmission/gearbox, not the combustion system. Engine lubrication comes from pre-mix fuel.
  • Factory specification for transmission oil capacity: approximately 660ml (0.69 US quarts)
  • Drain bolt torque:– 14 ft-lbs (as per typical YZ125 procedure)
  • Side fill and check bolts lie below the right engine case; use a long funnel to avoid the expansion chamber
  • Include a new washer on the drain bolt to ensure a proper, leak-free seal; failure to use a washer can lead to drips or bolt damage

Step-by-Step Oil Change Instructions

  1. Warm Up the Engine
    • Start the bike and let it idle for 2-3 minutes. This warms the oil, allowing it to drain quickly and completely.
    • Turn off the engine and ensure the bike is upright and on level ground, using a stand if available.
  2. Remove the Drain Bolt
    • Place your drain pan under the engine. The drain bolt is located at the bottom of the right engine case.
    • Use the 12mm socket to remove the drain bolt. Use caution–the oil may be hot.
    • Allow all oil to drain. Inspect the condition of the drained oil for metal shavings or unusual debris, a sign of possible wear.
  3. Replace the Drain Bolt Washer and Reinstall the Drain Bolt
    • It's good practice to use a new crush washer on the drain bolt each time. This helps maintain a tight seal.
    • Reinstall the drain bolt by hand to avoid cross-threading, then use your torque wrench to tighten to 14 ft-lbs.
    • The washer should compress slightly as you approach proper torque.
  4. Add Fresh Oil
    • Remove the oil fill cap from the right engine cover.
    • Use a measuring cup to pour in exactly 660ml (0.69 US quarts) of recommended 10W-40 (wet clutch compatible) transmission oil.
    • To avoid spills, use a long funnel positioned under the exhaust pipe.
  5. Check the Oil Level (Optional but Recommended)
    • Locate the oil check bolt (on some models, a small bolt next to the fill cap; on others, it may be a sight glass or window).
    • Remove the check bolt with a 4mm Allen wrench.
    • If oil dribbles from the hole, the transmission is properly filled. If not, add a tiny amount more oil until it appears at the check hole, then reinstall the bolt.
  6. Replace the Fill Cap and Clean Up
    • Replace the fill cap securely. Wipe away any spills or drips.
    • Start the bike, let it idle for one minute, then check for leaks at the drain plug and fill cap.
    • Properly dispose of used oil at a recycling center–do not pour it on the ground or into drains.

Important Details for 2024 YZ125 Owners

  • Change your transmission oil after every 5-10 hours of heavy riding or after muddy/harsh conditions for best clutch and gearbox life.
  • Always use wet clutch-compatible oil specifically designed for 2-stroke gearboxes. Automotive engine oils can cause clutch problems.
  • Check for leaks at the drain and fill plugs after your first ride post-change.
  • This procedure will not lubricate your engine top end—always use proper pre-mix ratios in your fuel as per Yamaha specs (typically 30:1 with YAMALUBE "2-R" or similar two-stroke oil).

Conclusion

Routine transmission oil changes on your 2024 Yamaha YZ125 maximize gearbox durability and clutch performance. With simple tools and less than 30 minutes, you can perform this essential task and keep your bike ready for any track or trail. For top-tier OEM and aftermarket parts, trust MotoSport.com as your dirt bike headquarters.

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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.