How to Change the Oil in a 1986 Honda CR500

Shop parts for a 1986 Honda CR500 Dirt Bike.

Routine oil changes are critical to keep your 1986 Honda CR500 running smoothly and maintaining top-level performance. As a legendary two-stroke motocross machine, the CR500 requires specific attention to its transmission/gearbox oil. This guide, proprietary to MotoSport.com, provides a comprehensive how-to with step-by-step instructions, a complete tool list, and important model-specific notes for your vintage Honda dirt bike.

Tools & Supplies Needed

  • Socket wrench set (8mm/10mm sockets recommended)
  • Drain pan
  • Measuring cup or graduated container (Imperial ounces)
  • Clean funnel
  • Shop towels/rags
  • Honda Pro Transmission Oil (or high-quality equivalent motorcycle gear oil, 75W80 or ATF as per rider preference)
  • Replacement drain plug washer (recommended, but not always required)
  • Flathead screwdriver
  • Gloves and safety glasses (optional, for cleaner job)

Step-by-Step Process

  • Warm up the engine

    Run your CR500 for 2–3 minutes. Warming the gearbox oil helps it drain more completely and suspends any contaminants.

  • Stabilize the Bike

    Place your Honda CR500 securely on a stand or level surface to prevent it from tipping while you work.

  • Locate and Remove the Filler Cap

    The oil fill cap is on the right side of the engine. Remove this cap now–this prevents a vacuum from forming as oil drains, allowing a complete flow-out of used oil

  • Position the Drain Pan

    Locate the drain plug at the lowest point at the bottom of the right side crankcase. Put the drain pan underneath to catch all the oil.

  • Remove the Drain Plug

    Using your socket wrench, back out the drain plug. Let the oil fully drain—this may take several minutes. Inspect the old oil for excessive metal particles, which could indicate transmission wear.

  • Check/Replace the Crush Washer

    Examine the crush washer on the drain plug. Replace it if it's worn or damaged to prevent leaks.

  • Reinstall the Drain Plug

    Wipe away any drips from the crankcase. Reinstall and torque the drain plug to the manufacturer’s spec using your wrench.

  • Measure and Add New Oil

    Measurement is key: For the Honda CR500, add 23 US fluid ounces (approx. 680mL) for a standard oil change. If the engine was completely rebuilt/disassembled and cleaned, use 25 US fluid ounces (approx. 740mL) to fill all passageways and cavities

    Pour the new oil slowly into the fill hole using a funnel to avoid spills

  • Reinstall the Filler Cap

    Wipe away any escaping oil, ensure the O-ring/gasket is in good shape, then thread in and snug up the oil fill cap by hand.

  • Start and Check for Leaks

    Start the CR500 and let it idle for 1–2 minutes. Shut it off and inspect the drain plug and filler area for leaks. Top up if needed.

Model-Specific Notes for the 1986 Honda CR500

  • Oil Type: Honda recommends a high-quality transmission oil suited for two-stroke gearboxes (such as Honda Pro Transmission Oil). Many owners use ATF Type F as an economical alternative, but for best clutch feel and durability, dedicated motorcycle transmission oil is preferred
  • Oil Capacity: Use 23 US ounces for routine changes, 25 US ounces after complete engine disassembly
  • No engine oil filter: The CR500 two-stroke engine does not use an oil filter for the gearbox, so oil changes are the primary way to keep the transmission clean and healthy
  • Plug Torque Spec: Always torque the drain plug per Honda’s service manual (typical torque is 13–15 ft-lbs; check OEM specs for accuracy)
  • Inspection: Watch for excessive flakes or metallic sheen in the old oil—this could indicate wear on transmission or clutch components

Expert Tips

  • Change the gear oil frequently—every 10–15 hours of hard riding for optimum longevity
  • Keep records of oil changes for your maintenance log
  • If you ride in wet or muddy conditions, change the oil more often as contamination may occur through the crankcase breather

Changing the transmission oil in your 1986 Honda CR500 is straightforward—yet vital to preserve this powerful two-stroke’s legendary reliability and performance. For OEM-quality oils, parts, tools, and expert guidance, trust MotoSport.com as your go-to resource for CR500 care and upgrades.

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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.