How to Change the Oil in a 1980 Honda CR125 – MotoSport.com Guide

Shop parts for a 1980 Honda CR125 Dirt Bike.

Changing the oil in your 1980 Honda CR125 is a critical maintenance task that ensures your dirt bike's transmission and clutch system run smoothly. This detailed step-by-step guide will walk you through everything you need for a successful oil change, along with specific tips for your make, model, and year. Whether you're preparing for your next ride or just keeping up with essential bike care, this process will help prolong the life of your CR125.

Tools & Materials Needed

  • 17mm socket or wrench (for the drain plug)
  • Socket wrench or spanner
  • Drain pan
  • Funnel
  • Clean rags or paper towels
  • New oil (typically 10W-40 motorcycle transmission oil, check your owner's manual for exact specification)
  • Aluminum sealing washer (replace if crushed or worn)
  • Triangle stand or bike stand (optional, but helps steady your CR125)
  • Gloves (optional, but keeps your hands clean)

Step-by-Step Process

  • Warm Up the Bike:
    • Start your bike and let it idle for 1-2 minutes. This warms the oil, allowing it to drain more thoroughly and carry out more contaminants.
  • Stabilize the Dirt Bike:
    • Set the CR125 on a triangle stand or steady the bike so it is upright and level. This ensures all old oil will drain out properly.
  • Locate the Drain Plug:
    • The oil drain plug is located directly beneath the engine case. On the 1980 CR125, it's a 17mm bolt at the base of the clutch side.
  • Position the Drain Pan:
    • Place the drain pan directly under the drain plug to catch dirty oil.
  • Remove the Drain Plug:
    • Using your 17mm socket or wrench, carefully loosen and remove the drain bolt. Let the oil drain completely (allow several minutes for thorough draining).
    • Check the aluminum sealing washer for wear or damage. Replace it if it appears crushed or deformed.
  • Remove the Fill Cap and Check Bolt:
    • The oil fill cap is located on the top side of the clutch cover. Remove it to allow air flow, which helps the oil drain faster.
    • There is also an oil check bolt on the side of the case—this helps you verify proper oil level after refilling, but it's not necessary for draining.
  • Inspect and Clean:
    • While the oil drains, inspect the removed drain plug for metal shavings. A small amount of fine metallic debris is typical for two-strokes, but large pieces can indicate internal wear.
    • Wipe the drain plug and threads clean with a rag.
  • Reinstall the Drain Plug:
    • Once oil has fully drained, reinstall the drain plug with a new or good sealing washer. Hand-tighten, then snug it up with a wrench—do not overtighten, as the case is aluminum and threads can strip easily.
  • Refill With Fresh Oil:
    • Place a funnel into the fill hole at the top of the clutch cover. Pour the recommended volume of transmission oil:
    • Specific call-out for 1980 CR125: The transmission typically requires approximately 650cc (~0.69 quarts). Always double-check your owner's manual, as running too much or too little oil can affect clutch function and transmission longevity.
    • Use the oil check bolt (if equipped) on the side cover to ensure you have the correct amount—oil should seep out slightly when the correct level is reached.
  • Reinstall the Fill Cap:
    • Once oil is at the proper level, hand-tighten the fill cap securely.
  • Clean Up and Check for Leaks:
    • Wipe away any spilled oil, clean your tools, and start the engine. Let it idle, then check for any signs of leaks around the drain plug and fill cap.

Important Notes for the 1980 Honda CR125

  • Oil Specification: The 1980 CR125 does not use engine oil for the crankcase—oil changes apply to the transmission/clutch compartment. Always use a modern 10W-40 non-friction-modified oil designed for wet clutches.
  • Capacity: Approximately 650cc (0.69 quarts), but verify with your manual. Overfilling can cause clutch drag; underfilling can increase wear or cause shifting issues.
  • Washer Replacement: The aluminum sealing washer on the drain bolt should be replaced if deformed to ensure a reliable seal.
  • Check for Leaks: Aluminum cases strip easily—hand-tighten bolts and use a torque wrench to manufacturer spec if possible.
  • Maintenance Interval: Change your gearbox oil every 5-10 hours of riding, or after every race or muddy/wet ride, to keep the transmission and clutch in top condition.

Order Your Supplies at MotoSport.com

For all your maintenance needs, including Honda CR125 oil, gaskets, and tools, visit MotoSport.com for a full selection of parts designed for your 1980 CR125. Proper care will keep your vintage race machine running strong for years to come.

Conclusion

Routine oil changes are vital to protecting the transmission and clutch of your 1980 Honda CR125. With the right tools, a little patience, and quality oil, you can keep your bike performing at its best on and off the track.

Related Shopping Categories

Shop Motor Oil for a 1980 Honda CR125 Dirt Bike.

Shop Oil Filters for a 1980 Honda CR125 Dirt Bike.

Shop Oil Drain Pans for a 1980 Honda CR125 Dirt Bike.

Shop Tools for a 1980 Honda CR125 Dirt Bike.

Shop Oil Fillers and Drain Plugs for a 1980 Honda CR125 Dirt Bike.

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.