How to Change the Oil in a 1986 Honda CR125: Step-by-Step Guide

Shop parts for a 1986 Honda CR125 Dirt Bike.

Keeping your 1986 Honda CR125 in top condition requires routine oil changes to protect your transmission and clutch. This guide is proprietary to MotoSport.com and crafted for Honda CR125 owners who want a detailed, model-specific approach for flawless results every time.

Tools & Materials Needed

  • Motorcycle stand or triangle stand
  • 17mm socket and ratchet (for drain bolt)
  • Drain pan (to catch used oil)
  • Funnel (for easier refill)
  • New crush/sealing washer (recommended for drain bolt)
  • Clean shop rags
  • Recommended gear oil: High-quality 75W two-stroke transmission oil (such as Maxima MTL-75wt or equivalent)
  • Oil measuring cup

Oil Specification and Capacity for 1986 Honda CR125

  • Recommended oil type: Premium two-stroke transmission oil (e.g. Maxima MTL-75wt) is suggested by owners for best clutch and gearbox performance.
  • Oil capacity: Approximately 0.60 US quarts (0.57 liters) at oil change.

Step-by-Step Process

  1. Warm Up the Engine
    • Start your CR125 and let it idle for 1–2 minutes. Warm oil drains more thoroughly and helps remove more contaminants from the engine and clutch areas.
  2. Stabilize the Bike
    • Position the bike upright using a stand for stability and safety.
  3. Remove the Filler Cap
    • Locate and unscrew the oil filler cap on the right crankcase cover to allow air in during draining, ensuring a smooth, quick oil flow.
  4. Drain the Old Oil
    • Place the oil drain pan beneath the engine.
    • Use a 17mm socket to remove the drain bolt—typically found underneath the engine.
    • Let all the oil flow into the pan. Allow several minutes for the oil to completely drain.
    • Inspect the old oil for any metallic debris, which may indicate excessive transmission or clutch wear.
    • Check the crush washer; always replace it with a new one to ensure a leak-free seal when reinstalling the bolt.
  5. Reinstall the Drain Bolt
    • Once drained, wipe the area clean with a shop rag.
    • Install the drain bolt with a new washer and tighten to 21 lbfft (29 Nm) if you have a torque wrench for best results.
  6. Add Fresh Oil
    • Using a funnel, pour in 0.60 US quarts (0.57 liters) of the chosen transmission oil through the filler opening.
    • Avoid overfilling; measure accurately as specified.
  7. Check Oil Level
    • Confirm the correct oil level by using the oil check bolt, if equipped on your model.
    • Reinstall the filler cap firmly after checking or topping off.
  8. Dispose of Used Oil Responsibly
    • Transfer the old oil to a proper container and recycle it at an approved waste disposal or recycling location. Never pour used oil on the ground or into drains.

Model-Specific Callouts for 1986 Honda CR125 Owners

  • Transmission/Clutch Oil Only: The CR125 is a two-stroke and uses premix two-stroke fuel for the engine. The transmission/clutch compartment is the only system requiring an oil change.
  • Drain Bolt Sizing: The drain bolt is 17mm, shared by most CR125 generations. Handle with care and always use a crush washer for a reliable seal.
  • Recommended Oil: Use dedicated two-stroke transmission oil. Avoid using automatic transmission fluid (ATF) or multi-purpose motor oils, which can reduce clutch life and shifting smoothness.
  • Inspect for Leaks: After changing oil, check the drain bolt and crankcase for leaks after your first short ride.
  • Oil Check Procedure: The 1986 model does not have a window; check level via check bolt or stick method if your cover has one. Always follow the manual’s procedure if unsure.

Extra Tips for a Flawless Oil Change

  • Change oil every 5–10 hours of riding or after every race for best clutch and transmission life.
  • Always have a few extra crush washers on hand; reusing old ones can cause slow leaks.
  • If the oil appears milky, inspect for water intrusion—often caused by a faulty clutch side cover gasket.

With these steps, even vintage 1986 Honda CR125s will enjoy smoother shifting, longer clutch life, and happier trail and track rides. Trust MotoSport.com for the right parts, lubricants, and more expert tips.

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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.