How to Change the Oil in a 1986 Yamaha PW50

Shop parts for a 1986 Yamaha PW50 Dirt Bike.

Keeping your Yamaha PW50 running smoothly requires regular maintenance, and changing the transmission oil is a crucial part of that. Here's a detailed, easy-to-follow guide, proprietary to MotoSport.com, outlining the steps, tools needed, and important call-outs specific to this make, model, and year. The process below ensures you get reliable performance and longevity from your vintage PW50.

Tools and Supplies Needed

  • 12mm socket wrench (for drain bolt removal)
  • Torque wrench (capable of 10 foot-pounds / 14 Nm)
  • Drain pan (to catch old oil)
  • Replacement transmission oil (0.30L of motorcycle-rated oil, never use energy-conserving or oils rated above SAE "CD" for diesels)
  • New crush washer/gasket for the drain bolt (recommended for every oil change)
  • Clean rags or shop towels
  • Funnel (optional, for easy refilling)

Preparation Steps

  • Ensure the engine is warm but not hot; running the engine for a few minutes helps the oil drain completely and quickly (be cautious, as the exhaust and engine will be warm) .
  • Put the bike on its centerstand or a stable stand to keep it upright and secure .

Step-by-Step Oil Change Guide

  1. Remove the oil filler cap:
    • The filler cap is located on top of the transmission. Removing it before draining allows the oil to flow out freely .
  2. Place a drain pan under the transmission:
    • Position the drain pan to catch all the used oil as it's released from the case .
  3. Remove the drain bolt:
    • Use a 12mm socket to loosen and remove the drain plug from the bottom of the transmission. Be sure to keep track of the crush washer/gasket on the bolt .
    • Allow all oil to drain completely into the pan. This may take several minutes.
  4. Inspect and clean:
    • Wipe the drain plug clean and install a new crush washer if available. Clean any debris or oil from the plug and mating surfaces .
    • Check the O-ring on the filler cap for damage, cracks, or deformation–replace if necessary .
  5. Reinstall the drain bolt:
    • Thread in the drain plug by hand to prevent cross-threading, then tighten with the torque wrench to the manufacturer's specification: 10 foot-pounds (14 Nm) .
  6. Refill with new transmission oil:
    • Using a funnel if needed, pour 0.30 liters (300 ml) of recommended transmission oil into the filler hole .
    • Confirm oil type requirements: Do not use any chemical additives, diesel-spec "CD" or better, nor "Energy Conserving II" or higher rated oils. This is strictly to prevent clutch slippage or premature wear (important for all PW50s, including your 1986 model) .
  7. Replace and tighten the filler cap:
    • Install the cap securely. Do not overtighten.
  8. Run the engine and check:
    • Start the engine and let it idle for a few minutes, then check under the bike for leaks .
    • If you spot any leaks, immediately shut off the engine and recheck the drain bolt, washer, and filler cap seating.

Year-Specific Call-outs: 1986 Yamaha PW50

  • All PW50 models, including 1986, use a shared transmission and clutch oil bath. Incorrect oil types or additives can cause rapid clutch wear or slipping. Always use only oil specified for this type of system, and do not substitute automotive or "energy conserving" engine oils .
  • The oil change volume (0.30L) is consistent across all years, but it's best to measure; overfilling can lead to pressure leaks or foaming .
  • Inspect the crush washer/gasket on the drain bolt closely. Reusing a deformed or old washer can lead to leaks, common with repeated oil changes through the decades .
  • Be gentle when torquing bolts on this older model—over-torquing can damage the threads in the aluminum case.
  • 1986 did not include an oil filter to change separately; oil maintenance for the transmission is simply as outlined above.

Pro Tips for Best Results

  • Warm oil drains faster and carries away more sediment.
  • Dispose of old transmission oil properly according to your local environmental regulations.
  • Write down the date and hours (if available) of the service for your maintenance records.
  • Visually inspect for leaks or damage to the case, bolts, and fill/drain openings before your next ride.

By following these steps and adhering to the unique needs of the 1986 PW50, you'll keep your mini-moto reliable and ready for countless rides. If you have further questions or need model-specific kits and supplies, MotoSport.com has you covered.

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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.