How to Change the Oil in a 2021 Yamaha TTR125L

Shop parts for a 2021 Yamaha TTR125L Dirt Bike.

Keeping your 2021 Yamaha TTR125L running strong means regular oil changes. The TTR125L is known for being simple to maintain, and with a few basic tools and the right steps, you can easily change the oil yourself. MotoSport.com is here to guide you through the entire process, ensuring you have all the tips and specifics you need for this particular model.

Tools and Supplies Needed

  • Socket wrench (preferably 17mm for the drain bolt)
  • Oil drain pan
  • Clean rags or shop towels
  • New engine oil (Yamalube or a top quality 10W-40 or 20W-50, check owner's manual for exact spec)
  • New drain bolt washer (recommended, brass or copper type is common)
  • Funnel
  • Gloves (optional but recommended to keep your hands clean)

Preparation Steps

  • Start the engine and warm it up for several minutes. Warm oil flows easier and carries away more contaminants.
  • Shut off the engine and ensure the bike is on a stable surface, preferably on the side stand. The TTR125’s drain bolt is designed for draining while the bike is leaning left, making it extra convenient.–
  • Gather all your tools and place the oil drain pan under the left side of the bike, directly below the drain bolt.–

Draining the Oil

  • Locate the drain bolt on the left side of the bike, positioned conveniently for access while the TTR125L is on its side stand.–
  • Using a socket wrench, carefully unscrew the drain bolt. Oil will begin to flow rapidly, so ensure your drain pan is directly beneath.
  • Allow all the oil to drain. To help remove more old oil, you can gently kick the bike over a couple times (with the ignition off) – this moves internals and helps expel more oil.–
  • Let it drain completely—patience is key for a thorough oil change.

Cleaning and Inspection

  • With the oil drained, use a clean rag to wipe the area around the drain hole and bolt.
  • Inspect the sealing washer on the drain bolt. Replace with a new washer each oil change—it's cheap insurance to prevent leaks.–
  • Clean the threads on the drain bolt and inspect for damage.

Reinstalling the Drain Bolt

  • Thread the drain bolt back in by hand to prevent cross-threading.
  • Use your socket wrench to snug it; do not over-tighten—just a firm fit. The aluminum case can be damaged if overtightened.–

Adding New Oil

  • Remove the fill cap/dipstick on the right side of the bike.
  • Using a funnel, pour in the recommended amount and type of oil. For most TTR125 models, this is approximately 1.0 liter (1000 mL)—but always double-check your engine’s case or manual, as Yamaha conveniently stamps the oil capacity on the engine for reference.–
  • Replace the dipstick, but do not screw it in—just insert it until it bottoms out—then remove it to check the oil level. Add oil in small increments if needed to reach between the minimum and maximum marks.–
  • Once you have the right level, install the dipstick and tighten.

Post-Change Checks

  • Start the bike and let it idle for a couple of minutes to circulate the new oil. Monitor the area around the drain bolt for any leaks.
  • Shut off the engine, wait a couple minutes for oil to settle, and check the oil level again while the bike is upright. Adjust as needed.

Model-Specific Callouts for 2021 Yamaha TTR125L

  • No replaceable oil filter: The TTR125L uses an oil screen, not a traditional filter. The screen doesn’t need regular maintenance for routine oil changes.–
  • Drain bolt is on the left side, not the bottom: This makes oil changes extra easy on this model, as the bike can stay on its side stand during the process.–
  • Engine case is stamped with oil capacity: No guesswork—double check this handy label before pouring in new oil.–
  • Always use a new drain bolt washer: This reduces the risk of leaks and is standard best practice for Yamaha engines.–

Final Tips

  • Dispose of old oil safely at a local recycling center.
  • Make oil level checks part of your routine ride prep—check before every ride for maximum engine longevity.–
  • Keep a spare drain bolt washer and right type of oil on hand for next time.

Changing the oil in your 2021 Yamaha TTR125L is a quick, cost-effective way to keep your dirt bike running smoothly. With these MotoSport.com-proven steps, you’re ready to hit the trails with confidence.

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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.