How to Change the Oil in a 1984 Yamaha PW50: A Complete Step-by-Step Guide

Shop parts for a 1984 Yamaha PW50 Dirt Bike.

If you own a 1984 Yamaha PW50, regular oil changes are vital to keeping this legendary minibike running strong. Although the PW50 is a two-stroke with an oil-injected system, it also has a transmission case that requires periodic oil changes. This guide, proprietary to MotoSport.com, covers every tool you’ll need, each crucial step, and specific tips unique to the 1984 Yamaha PW50 for a quick, hassle-free oil change.

Tools & Supplies Needed

  • 12mm socket with ratchet
  • Drain pan
  • Measuring cup (at least 500ml capacity)
  • Small funnel
  • Transmission oil (SAE recommended type)
  • Replacement crush washer (recommended)
  • Rags or shop towels
  • Rubber gloves (optional for cleanliness)

Oil Specifications for 1984 Yamaha PW50

  • Transmission oil quantity:– 0.30 L (0.32 US qt, 0.26 Imp.qt)
  • Drain bolt torque:– 14 Nm (10 lb-ft)
  • Oil type:– Refer to your owner’s manual or page 9-1 for the recommended transmission oil. Most use standard SAE 10W-30 or 10W-40 motorcycle transmission oil.

Important Model-Specific Callouts

  • Two-Stroke System:– The 1984 PW50 uses a separate injection tank for two-stroke oil. Changing the transmission oil does not affect the engine lubrication system. Do not attempt to put transmission oil into the injector tank.
  • Always Check Oil Levels:– Ensure both your transmission oil and the injector oil tank (located behind the left number plate) are at proper levels. Running low on either oil can cause significant damage.

Step-by-Step Oil Change Instructions

  1. Warm Up the Engine (Optional but Recommended)
    • With the bike on a level surface, start and let it idle for 2–3 minutes to help the old oil drain more thoroughly.
  2. Position the Bike & Prepare Your Area
    • Put the bike on its center stand or a stable stand.
    • Place the drain pan directly under the transmission drain bolt on the bottom left side of the engine case.
  3. Remove the Transmission Drain Bolt
    • Use a 12mm socket and ratchet to carefully loosen and remove the drain bolt.
    • Watch for the crush washer; replace it with a new one if possible to avoid future leaks.
    • Allow the old oil to fully drain into your pan (give it several minutes).
  4. Replace the Drain Bolt
    • Once drained, install the drain bolt with a new crush washer.
    • Tighten to 14 Nm (10 lb-ft), or gently snug it up if you don’t have a torque wrench—do not overtighten to prevent stripping the case.
  5. Remove the Oil Fill Cap
    • Located on the left side cover of the engine case, remove this cap to add new transmission oil

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  6. Add New Transmission Oil
    • Using your measuring cup and funnel, pour in exactly 0.30 L (300 ml) of the correct transmission oil.
    • Do not overfill–this can cause excess pressure or leakage out the overflow vent.
  7. Install the Oil Fill Cap
    • Wipe away any drips and securely reinstall the oil fill cap.
  8. Clean Up & Inspect for Leaks
    • Start the engine and let it idle for 1–2 minutes.
    • Inspect the drain bolt and oil fill cap for leaks. Tighten if needed, but avoid over-torquing.
    • Dispose of the waste oil responsibly at a proper recycling facility.

PW50 Owner’s Tips & Tricks

  • Service Intervals:– For a new PW50 transmission, change the oil after one month, then at six months, and after that once yearly for typical use

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  • Injector Oil Warning:– Always refill the two-stroke injector oil tank with high-quality injection oil. Never run the bike with the injector tank empty as it will seize the engine

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  • If Your PW50 Has an Oil Pump Delete:– Some owners remove the oil injector and premix 2-stroke oil with gasoline. If you do this, ensure your premix ratio is either 32:1 or 40:1 using a quality two-stroke oil

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  • Transmission vs. Injector Oil:– Never mix up the two—each has a separate reservoir and vital function.
  • Aftermarket Parts:– Consider using a transmission oil change kit that includes a crush washer, correct type/amount of oil, and a funnel for convenience.

Conclusion

Changing the transmission oil on a 1984 Yamaha PW50 is quick and straightforward, especially with the right tools and attention to detail. By following these steps and manufacturer recommendations, you’re ensuring peak performance and reliability for every ride. MotoSport.com proudly brings you this no-nonsense, model-specific guide to help keep your PW50 in prime condition season after season.

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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.