How to Change the Oil in a 1983 Yamaha PW50

Shop parts for a 1983 Yamaha PW50 Dirt Bike.

Regular oil changes are essential to keep your 1983 Yamaha PW50 running smoothly and to prolong the life of its transmission. This step-by-step guide will walk you through the process with all the model-specific tips, the correct oil type and volume, and a comprehensive tool list. Changing the oil on a PW50 is straightforward—a great project for DIYers and parents introducing kids to basic dirt bike maintenance.

Tools & Supplies Needed

  • 12mm socket and ratchet – for the drain plug
  • Drain pan – to catch old oil
  • Funnel – for adding new oil
  • Clean rags or paper towels – to wipe up spills
  • New washer (crush washer) – to replace the old washer on the drain bolt
  • Torque wrench – recommended for proper bolt tightening
  • Transmission oil – Yamaha specifies 80/90W gear oil or similar
  • Measuring cup – needed for accurate oil measurement
  • Nitrile gloves – optional but helps with cleanup

Key Specifications for 1983 Yamaha PW50

  • Your bike uses a two-stroke engine with a separate transmission oil chamber. Never put engine oil in the gas tank; use two-stroke oil for the injector system.
  • Transmission oil capacity is 300ml (about 10.1 US ounces).
  • The drain bolt torque spec is 10 foot-pounds (approximately 14 Nm)—do not overtighten.
  • Recommended oil: Any high-quality SAE 80/90W gear oil.

Step-by-Step: How to Change the Oil

  1. Warm up the bike.
    Start and let your PW50 idle for just a minute or two. This helps the oil flow more easily and ensures thorough drainage.
  2. Put the bike on a secure stand.
    Stabilize the bike in an upright position with a stand or flat level surface.
  3. Locate the drain plug.
    Find the transmission oil drain bolt underneath the engine. It takes a 12mm socket.
  4. Place the drain pan underneath the engine to catch the oil.
  5. Remove the drain plug.
    • Use the 12mm socket to carefully loosen and remove the drain bolt.
    • Note the crush washer – this thin metal washer sits under the drain bolt, and it should be replaced with a new one to ensure a proper seal and prevent leaks.
  6. Remove the oil fill cap.
    While oil drains, loosen and remove the oil fill cap on top of the engine. This allows air to enter, speeding up draining and allowing better inspection of the cap for debris.
  7. Wait for the oil to drain completely.
    Take your time—let it drip until only the occasional drop falls into the pan.
  8. Clean and inspect.
    • Wipe the drain plug clean, making sure no old oil or debris is present.
    • Remove the old crush washer from the plug and replace it with a new one.
    • Clean any oil residue around the fill area and threads.
  9. Reinstall the drain plug.
    • Thread the bolt back in by hand to avoid cross-threading.
    • Use your torque wrench to tighten the plug to 10 foot-pounds.
  10. Add fresh oil.
    • Use the measuring cup to pour in 300ml of 80/90W gear oil.
    • Pour oil into the fill hole using a funnel to avoid spills.
  11. Replace and tighten the oil fill cap.
  12. Check for leaks.
    • Wipe down any excess oil.
    • Start the bike and let it idle for 1-2 minutes.
    • Check around the drain plug and fill cap for drips or leaks.
  13. Dispose of old oil properly.
    Take the used oil to a recycling facility or auto parts store—never pour it down drains or onto the ground.

PW50 Owner Specific Call-Outs

  • This bike has an oil-injection system. Make sure to keep your two-stroke injector oil reservoir full with two-stroke injection oil, not engine oil. The injection system is fully separate from the transmission oil you’re changing here.
  • Inspect the oil pump during routine maintenance. If your pump isn’t functioning properly, it could over- or under-oil the engine, leading to major wear or damage. Listen for unusual noises and check oil levels regularly. If you suspect an issue with your oil pump, refer to a specialist or consult a dedicated manual before riding.
  • The drain plug washer (crush washer) should always be replaced to avoid leaks.
  • Changing your PW50’s oil every 10-20 riding hours, or at least once per riding season, is a good rule of thumb.
  • The 1983 model uses minimal electronics and no oil filter as part of the oil change process, making the job simple compared to most modern dirt bikes.

Final Notes

  • Always double-check you’ve added the right type and amount of oil, and that you have no leaks after changing.
  • Store the bike upright—storing it on its side or at a wrong angle can cause oil to leak from the fill vent.

For more Yamaha PW50 parts, oil kits, and riding tips, MotoSport.com remains your one-stop shop for everything dirt bikes.

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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.