How to Change the Oil in a 1989 Kawasaki KX125: A Comprehensive Guide by MotoSport.com
Shop parts for a 1989 Kawasaki KX125 Dirt Bike.
Routine oil changes are critical for the longevity & performance of your 1989 Kawasaki KX125. This two-stroke dirt bike uses a separate transmission oil system, and regular servicing helps preserve clutch & gearbox life. This model, being over three decades old, can greatly benefit from diligent maintenance. Below you’ll find everything you need to tackle this job, from the required tools and supplies to KX125-specific call-outs for a safe, thorough oil change.
Tools and Supplies Needed
- Socket wrench set (primarily 12mm and 17mm sockets)
- Drain pan (large enough for used oil)
- Clean rags or shop towels
- Parts cleaner or degreaser
- New transmission oil (SAE 10W-40 motorcycle transmission oil is most commonly recommended for Kawasaki KX125 models–consult your owner’s manual, as some variations may apply)
- Measuring cup or graduated container (for precise oil refill–1989 KX125 capacity is typically around 700 mL, but always refer to your manual for exact specifications)
- New drain plug washer (optional but recommended)
- Funnel
- Gloves and safety glasses
Step-by-Step Oil Change Procedure
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Warm Up the Engine (Optional but Helpful):
- Start your bike and let it idle for 2–3 minutes. Warm oil drains more thoroughly, helping to remove more contaminants. Turn off the engine before proceeding.
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Stabilize the Bike:
- Place the KX125 on a sturdy stand to keep it level and upright. This ensures a complete drain and prevents spills.
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Locate and Remove the Drain Bolt:
- The drain bolt is usually found on the bottom left side of the crankcase (beneath the transmission). Use a socket wrench to loosen and remove the bolt. Be careful—the oil can be hot.
- Position your drain pan underneath the bolt to catch all the oil.
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Drain the Old Oil:
- Allow the oil to fully drain, which may take several minutes. Wobble the bike back and forth gently (if needed) to help any trapped oil escape.
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Inspect and Clean:
- Check the drain bolt and its washer for wear. Replace the washer if it's deformed or damaged.
- Wipe the area around the drain hole with a rag, and inspect for metal shavings in the old oil, which can indicate transmission wear.
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Reinstall the Drain Bolt:
- Thread the bolt back in by hand to avoid cross-threading, then snug it down with a wrench. Do not overtighten; typical specs are about 13 ft-lb (always refer to your owner's manual).
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Refill with New Oil:
- Remove the transmission fill plug, usually located on top or on one side of the engine case.
- Using a funnel, pour in the recommended amount of oil (typically 700 mL for an ’89 KX125). Exact capacity may vary; always check your manual for precise measurement.
- Some bikes have a sight window or dipstick—use this to verify proper level if available.
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Reinstall the Fill Plug:
- Ensure the fill plug threads are clean and undamaged. Tighten until snug but do not overtighten.
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Check for Leaks:
- Wipe any spilled oil, start the engine, and let it idle for a moment. Shut off and inspect the drain and fill plug areas for leaks.
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Dispose of Used Oil Properly:
- Place your old oil in a sealed container and dispose of it at an approved recycling facility or local auto parts store.
KX125 Model-Specific Call-Outs and Tips
- The 1989 Kawasaki KX125 has a two-stroke engine where the transmission oil is separate from the fuel/oil premix.
It’s critical to use the correct type and quantity of transmission oil to maintain reliable clutch and gear function.
Do not use conventional motor oil—only use oil specified for two-stroke transmissions to avoid clutch slippage and poor shifting (see also: general oil practices for Kawasaki KX series). - The drain and fill plugs may be soft, especially after years of service. Take care not to strip the threads when removing or reinstalling them.
- Inspect the oil for metal particles, which may reflect excessive wear—if present, consider a deeper inspection of your gearbox components.
- Because this is an older bike, always check for oil leaks from the countershaft seal or around the drain bolt after each oil change.
- If the owner’s manual is not available, most two-stroke KX125 models in this era require approximately 700 mL of SAE 10W-40 transmission oil, but confirm according to your service reference or trusted parts supplier.
Conclusion: Keeping Your ’89 KX125 in Top Shape
Regular transmission oil changes are a vital maintenance task for the 1989 Kawasaki KX125. With the right tools, quality oil, and attention to the bike’s unique requirements, your KX125 can deliver many more years of reliable, high-revving dirt performance. If any step in this process seems challenging, always consult your service manual or reach out to the knowledgeable staff at MotoSport.com for guidance and high-quality replacement parts.
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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.