How to Change the Oil in a 1987 Yamaha YZ250 – MotoSport.com Guide

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The 1987 Yamaha YZ250 is a classic two-stroke motocross bike. While these bikes require less internal oil than four-strokes, it's crucial to regularly change the transmission oil to keep your clutch and gearbox operating at their best. This guide covers the step-by-step oil change process specific to the 1987 YZ250, highlighting essential tools and model-specific tips.

Tools & Supplies Needed

  • Socket wrench set (typically 8mm or 10mm for drain bolt and fill plug)
  • Drain pan (low-profile recommended)
  • Clean rags
  • New transmission oil (e.g., 80W MTL gear oil or 10W-40 motorcycle transmission oil, about 750 ml or as specified in your manual)
  • Measuring cup (Ratio Rite recommended for accurate pour-off)
  • Funnel (for easy refill)
  • Torque wrench (optional, for re-tightening drain bolt to spec)
  • Gloves (optional, but helps keep hands clean)

Before You Start: Model-Specific Callouts

  • The YZ250 two-stroke transmission oil lubricates only the clutch and gearbox — the engine is lubricated by pre-mixed fuel, not the oil you’ll be changing. This is different from four-stroke models where crankcase and transmission share oil.
    Do not expect to find or need to change an oil filter on this bike; there isn’t one.
  • Factory oil capacity is typically 750 ml (about 0.8 US quarts) but confirm with your owner’s manual or look for markings on the case near the sight window or fill plug.
  • Warming up the bike very briefly helps old oil flow out, but don’t get the engine too hot.
    If you don’t want to run the engine, you can tip the bike side to side to ensure oil is fully drained.

Step-by-Step Oil Change Instructions

  • 1. Clean the Area
    Wipe down the sides of your engine near the drain bolt and fill plug. This prevents debris from entering when you open up the case.
  • 2. Warm the Transmission (Optional, But Recommended)
    Start the bike and let it idle for 1-2 minutes to warm up the transmission oil. If you can’t ride or run the bike, skip this step but be aware the oil may drain more slowly when cold.
  • 3. Place the Drain Pan
    Turn the fuel off. Lean the bike upright using a stand and position a low-profile drain pan directly underneath the drain bolt on the bottom of the engine.
  • 4. Remove the Fill Plug
    Locate and remove the oil fill plug (typically on the right side, above the clutch cover). This vents the system and allows oil to drain faster.
  • 5. Remove the Drain Bolt
    Use a socket wrench to carefully remove the oil drain bolt located at the bottom of the case. Keep the bolt and washer clean and set aside.
  • 6. Drain the Oil
    Let the transmission oil flow out completely. To ensure complete draining, you can tilt the bike gently from side to side over the pan. Watch for any signs of metal shavings in the oil, as these could indicate internal wear.
  • 7. Inspect and Reinstall the Drain Bolt
    Inspect the drain bolt washer for wear or deformity. Replace the washer if needed. Reinstall the bolt and tighten securely; if you have a torque wrench, follow the spec outlined in your owner’s manual.
  • 8. Add New Transmission Oil
    Use a measuring cup to pour in the specified amount of new oil (typically 750 ml of 80W MTL or 10W-40 motorcycle transmission oil). Use a funnel to avoid spills.
  • 9. Reinstall the Fill Plug
    Replace and tighten the fill plug. Wipe any spilled oil and check for leaks at the drain bolt.
  • 10. Check the Oil Level
    Some YZ250 models have a small sight bolt or window; remove it briefly to check for overflow when filling. Oil should just drip out of the inspection bolt hole when filled accurately. Otherwise, check the level after running the bike for a short time and top up as needed.
  • 11. Clean Up
    Dispose of the old oil according to local regulations. Wipe off any tools and address any leaks you may see.

Extra Tips for the 1987 YZ250

  • Use only motorcycle-specific transmission oils — avoid automotive oils.
  • The 1987 model does not use a filter; oil changes are the best way to keep your clutch and gears in good shape.
  • If unsure of the last change or oil used by a previous owner, consider changing oil after just a couple of rides to flush any contaminants.
  • Don’t over-tighten the drain bolt — aluminum threads can strip easily on vintage cases.

Keeping your 1987 Yamaha YZ250’s transmission oil fresh is one of the simplest yet most important ways to ensure a long and healthy life for its high-revving two-stroke engine. Regular oil changes will keep your gearbox shifting crisply and your clutch performing at its best. For quality parts and supplies, trust MotoSport.com — your one-stop shop for everything dirt bike.

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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.