How to Change the Oil in a 1987 KAWASAKI KX125: A Step-by-Step MotoSport.com Guide

Shop parts for a 1987 Kawasaki KX125 Dirt Bike.

Regular oil changes are vital for the performance and longevity of your 1987 Kawasaki KX125. As a 2-stroke dirt bike, the KX125’s oil system mainly lubricates the transmission and clutch. Follow this comprehensive guide, exclusive to MotoSport.com, to ensure your KX125 runs smooth and strong.

Tools and Supplies Needed

  • Socket wrench set (with appropriate metric sizes)
  • Drain pan
  • Clean rags
  • Funnel
  • Flathead screwdriver
  • New transmission oil (consult your manual for type and capacity; typically 10W-40 or 80W/85W gear oil)
  • Torque wrench
  • Gloves and safety glasses

Step-by-Step Oil Change Instructions

  1. Prepare Your KX125
    • Warm up the engine for a few minutes to allow the oil to drain easily. Shut off the engine and place the bike upright on a stand.
    • Make sure the area is well-ventilated and free from flames or sparks. Avoid smoking during the process.
  2. Locate the Drain Plug
    • The drain plug is on the bottom of the transmission side (right engine case) of the 1987 KX125. Place a drain pan directly underneath.
    • Use the proper sized socket or wrench to loosen and remove the drain plug. Be careful; the oil may be hot.
  3. Drain the Old Oil
    • Allow all old oil to fully drain out. Tilt the bike slightly if needed to remove as much as possible.
    • Inspect the magnetic tip of the drain plug for any metal shavings or debris. Clean it thoroughly before reinstalling.
  4. Reinstall the Drain Plug
    • Once drained, replace the drain plug and tighten it securely. Use a torque wrench to tighten to the manufacturer’s specification to avoid over-tightening or stripping the threads.
  5. Remove the Filler Cap
    • The filler cap is typically found on the clutch (right) side cover. Remove it.
  6. Add New Oil
    • Using a funnel, pour in the recommended type and quantity of transmission oil. For the 1987 KX125, this is usually approximately 600mL (refer to your service manual for precision).
    • Do not overfill; adding too much oil can cause foaming and poor clutch performance.
    • If your bike has a sight glass or level bolt, ensure the oil reaches the correct level.
  7. Reinstall the Filler Cap
    • Replace the filler cap and wipe away any spilled oil with a clean rag.
  8. Check for Leaks
    • Start your KX125 and let it idle for a minute. Check underneath and around the drain plug and filler for leaks.
    • Shut down the engine, let it sit for a minute, and re-check the oil level, topping off if necessary.

1987 KAWASAKI KX125: Model-Specific Call-Outs

  • This model is a 2-stroke. The oil change procedure is solely for the transmission/clutch area, not the engine’s combustion process (which relies on pre-mixed fuel).
  • When removing or installing any cover (such as the right engine case), drain the transmission oil first to avoid spilling oil inside your workspace (confirmed in KX service manuals).
  • Do not overfill. Overfilling can affect clutch operation. Only ever add oil up to the prescribed level, using the sight glass or check bolt if fitted.
  • Check and clean the oil plug magnet for metal debris as part of routine maintenance.
  • Use only the recommended oil type and grade as per your owner’s manual to prevent premature gear and clutch wear.

Troubleshooting Tips

  • If you see metallic flakes on the drain plug’s magnet, monitor closely during the next oil change. Persistent or significant debris may indicate gear or bearing wear.
  • Leaking drain or filler bolts usually result from damaged washers or over-tightening. Replace washers as needed and avoid excessive force.
  • If shifting feels stiff or the clutch drags after the oil change, double-check oil type and quantity.

Safety and Environmental Best Practices

  • Dispose of used oil responsibly at a recycling center; do not dump down drains or onto the ground.
  • Wear gloves to prevent irritation and always clean up any spills to avoid slips or environmental harm.

By following this MotoSport.com guide, you’ll keep your Kawasaki KX125 shifting smoothly and operating at peak performance for countless race seasons. For more exclusive repair and maintenance tips, stay tuned to MotoSport.com’s expert dirt bike resources.

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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.