How to Change the Oil in a 1985 Honda CR500 – Complete Step-by-Step Guide

Shop parts for a 1985 Honda CR500 Dirt Bike.

Changing the oil on your 1985 Honda CR500 is an essential maintenance task that keeps your dirt bike running smoothly and prolongs engine life. This guide is proprietary to MotoSport.com and designed specifically for the '85 CR500, covering all the tools you need, each step of the process, and key model-specific tips.

Tools and Supplies Needed

  • Socket wrench set (typically 12mm or 14mm for drain bolt)
  • Oil catch pan
  • Funnel
  • Clean shop rags
  • New gear oil (Honda recommends Pro Honda GN4 or a quality gear/transmission oil. Avoid engine or four-stroke oils.)
  • Torque wrench (recommended for drain bolt)
  • Service manual (for torque specs and reference)
  • Gloves (optional, for cleaner hands)

Critical Call-Out for the 1985 Honda CR500:

  • This bike is a two-stroke and uses a separate transmission (gear) oil – NOT engine oil. Do not use motor oils formulated for four-stroke engines.
  • Capacity is approximately 23 US fluid ounces (680 ml) for standard changes. For full disassembly or after a rebuild, use 25 US fluid ounces (740 ml) because more oil drains out. Always check the owner's manual for precise measurement for your year.
  • Common choices for transmission oil: Pro Honda Gear Oil or high-quality ATF (automatic transmission fluid), but manufacturer-branded gear oil is optimal for longevity and smoother shifts.
  • Fill cap location: On the right side of the engine, above the clutch cover – remove the fill cap during draining to prevent vacuum lock and ensure thorough emptying.

Step-by-Step Instructions

1. Warm Up the Engine

  • Start the CR500 and let it idle for about 2-3 minutes. This warms up the oil, helping it drain out smoothly and removing more contaminants.
  • Shut off the bike and ensure it’s securely upright – use a stand or have a helper hold it steady.

2. Locate Drain and Fill Plugs

  • The drain plug is at the bottom of the right engine case, typically a 12mm or 14mm bolt.
  • The fill cap is on the right side, above the clutch cover. Unscrew the fill cap before you remove the drain bolt to let air in and improve drainage.

3. Drain the Old Oil

  • Place the oil catch pan directly under the drain plug.
  • Using your socket wrench, carefully loosen and remove the drain plug.
  • Allow all the oil to fully drain out. Tip the bike slightly from side to side while it’s sturdy to remove more residue.
  • Wipe off the drain plug and check the sealing washer. Replace if it looks worn or deformed.

4. Inspect and Replace (if needed) the Oil Filter

  • The CR500's transmission does not use a conventional replaceable oil filter, unlike some four-stroke models. However, now is a good opportunity to clean around the fill and drain holes to prevent debris from entering during refilling.

5. Reinstall the Drain Plug

  • Thread the plug in by hand to avoid cross-threading.
  • Torque the drain plug to spec (usually 7-10 ft-lbs; check the owner's manual).

6. Add New Oil

  • Insert a clean funnel into the fill hole.
  • Pour in 23 US oz (680 ml) of fresh transmission oil.
  • If you have rebuilt the transmission, use 25 US oz (740 ml).
  • Wait for a few moments to let the oil settle.

7. Reinstall the Fill Cap and Final Checks

  • Screw the fill cap back on securely.
  • Wipe away any oil drips or smudges with a clean rag.
  • Start the bike and let it run for a minute, then shut it off and check for leaks at the drain and fill plug areas.

Pro Tips for 1985 CR500 Owners

  • Frequency: With hard off-road use, replace the oil every 5-10 hours of ride time or after any heavy weekend of riding.
  • Using specific motorcycle gear oil, like Pro Honda or Motul Transoil, results in quieter shifting and less clutch plate wear over time.
  • ATF alternative: Some riders use Type F ATF for a cheap and easy option, but it tends to get dirty faster and may require more frequent changes.
  • Always check your transmission oil level sight glass or bolt (if equipped) to ensure correct filling, especially if the bike has seen previous modifications.
  • Never overfill, as this can cause clutch drag or foaming inside the gearbox.

Common Mistakes to Avoid

  • Do not use four-stroke or engine oil – it lacks the right additives and can damage your clutch or gearbox.
  • Never reuse old oil; always change it when performing maintenance.
  • Over-tightening the drain plug can strip threads on the soft aluminum case. Use a torque wrench if possible.

Wrap-Up

Following these steps ensures your 1985 Honda CR500 keeps shifting smooth and running strong, whether you’re carving singletrack or hitting the dunes. For all your parts, oil, and filters, visit MotoSport.com – your source for genuine Honda maintenance supplies.

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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.