How to Change the Oil in a 1981 Suzuki RM250

Shop Parts for a 1981 Suzuki RM250 Dirt Bike.

Regular transmission oil changes are essential to keep your 1981 Suzuki RM250 performing at its best and to prolong the life of internal components. Below is a comprehensive, step-by-step guide exclusive to MotoSport.com, including the tools required, a walk-through of the procedure, and crucial tips specific to your classic RM250.

Tools & Supplies Needed

  • Socket Set (including Allen keys/hex wrenches)
  • Oil drain pan
  • Funnel
  • Cleaning rags
  • New crush washer (recommended for the drain bolt)
  • Torque wrench
  • Measuring cup (ideally marked in milliliters and ounces)
  • Fresh transmission oil (SAE 10W-40 motorcycle gear oil; check your manual for specification, as two-strokes like this use gear oil, not engine oil)
  • Gloves (to keep your hands clean and protected)

Specific Call-Outs for the 1981 Suzuki RM250

  • Two-stroke engines like the 1981 RM250 separate the engine and transmission lubrication. Only change the transmission oil – do not add oil to the engine crankcase.
  • This era RM250 has an oil check bolt for verifying oil level, located behind the chain guard and electrical harness on the left side. It's common for owners to overlook its placement, so be sure to locate it before draining and refilling.
  • Typical oil capacity is about 750 ml (refer to your owner’s manual for specifics ), but always double-check as some minor differences may exist between production years.

Step-by-Step Oil Change Instructions

  1. Warm Up the Engine:
    • Run your RM250 for a few minutes to warm the transmission oil. This allows it to flow out more easily and carry debris with it .
  2. Stabilize the Bike:
    • Put the motorcycle on a level surface and use a stand to keep it upright and secure.
  3. Remove the Oil Filler Cap:
    • The filler cap is located on the left side of the engine. Removing it before draining helps oil drain freely.
  4. Drain the Old Oil:
    • Place your oil drain pan directly under the drain bolt, found at the bottom of the engine.
    • Use the appropriate socket to remove the drain bolt. Allow oil to fully drain out. Clean any debris from the magnetic tip of the drain bolt if present.
    • Replace the crush washer if it's worn or deformed, and wipe the area clean.
  5. Reinstall the Drain Plug:
    • Reinstall and hand-tighten the drain bolt, then torque it to manufacturer specs – typically around 21 N·m (15 lb-ft) for the RM250 .
  6. Refill with Fresh Oil:
    • Use a funnel and pour in the correct amount of fresh 10W-40 oil (approx. 750 ml). Do not overfill.
  7. Check the Oil Level:
    • The RM250 features an oil check bolt on the left side, behind the chain guard and some electrical wires .
    • With the bike upright, remove the bolt with a hex/Allen key; oil should just begin to drip out if the level is correct. If none drips out, slowly add oil until it does, then replace and tighten the check bolt securely.
  8. Reinstall the Oil Filler Cap:
    • Double-check the filler cap gasket is in good condition and snug the cap back on.
  9. Run and Recheck:
    • Start the bike and let it run for a minute, then turn it off and let it sit for five minutes.
    • Verify there are no leaks and recheck your oil level as above, topping up if needed.
  10. Proper Disposal:
    • Dispose of old oil responsibly at a recycling center or auto parts store.

Pro Tips Exclusive to 1981 RM250 Owners

  • Never use automotive engine oil in the RM250’s transmission; always use motorcycle-specific gear oil.
  • Tighten all bolts to specification to avoid leaks or thread damage.
  • Check the condition of the drain bolt and check bolt O-rings and replace if they are cracked or flattened.
  • Changing transmission oil every 10–15 hours of riding is ideal for dirt riding; more frequent changes are cheap insurance for long-term reliability.
  • The oil check bolt’s placement behind the chain guard and wires can be frustrating — take your time and make sure the area is clean before opening it to prevent debris from entering the transmission .

Conclusion

Changing the oil in your 1981 Suzuki RM250 is straightforward if you work carefully and use the right products and procedures. Keeping up with routine oil changes will help ensure your classic two-stroke delivers reliable performance every ride.

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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.