How to Change the Oil in a 2006 Honda CR85 Big Wheel

Shop parts for a 2006 Honda CR85 Big Wheel Dirt Bike.

Keeping your Honda CR85 Big Wheel in top condition means regularly changing your transmission oil. The process is straightforward, but there are details specific to this model you need to know. This guide from MotoSport.com walks you step-by-step through the oil change, ensuring a clean, efficient, and safe job every time.

Tools and Supplies Needed

  • Correct oil (High-quality two-stroke transmission oil or recommended alternative)
  • Oil drain pan
  • Ratchet with appropriate socket (typically 12mm or 14mm; confirm size)
  • Funnel (small-tip style is ideal)
  • Rag or shop towels
  • Measuring cup or ratio cup (metric, in cc/milliliters)
  • Torque wrench (if available)

Preparing the Bike

  • Warm the engine briefly (1–2 minutes) to thin the oil for easier draining. Do not ride the bike; just idle gently.
  • Turn off the engine and place the bike upright on a stand or secure level ground.

Draining the Oil

  • Locate the oil drain bolt on the bottom of the engine case. It's usually on the left side, underneath the crankcase.
  • Place the oil drain pan directly underneath.
  • Using your ratchet and socket, carefully loosen and remove the drain bolt. Allow the oil to fully drain—tilting the bike slightly side to side will help remove all the old oil. Be careful not to overtighten or strip the bolt during removal or reinstalling.
  • Inspect the sealing washer on the drain bolt. Replace if it looks damaged or worn to prevent leaks.

Reinstalling the Drain Bolt

  • Once the oil has drained completely, clean the area around the drain hole and bolt.
  • Reinstall the drain bolt by hand to ensure it is not cross-threaded, then tighten with the ratchet. If using a torque wrench, aim for 21 ft-lb (28 Nm) if unsure, but confirm with your owner's manual.

Filling with New Oil

  • Remove the oil filler cap (on top or side of engine case, usually labeled OIL).
  • For the 2006 Honda CR85 Big Wheel (CR85RB), the standard oil fill is 650cc (or 0.65 liters). Verify this in the owner's manual or stamped on the engine case if possible.
  • Using a measuring (ratio) cup, pour in 500cc of oil first, then an additional 150cc to reach 650cc. A funnel with a small tip is ideal as the filler opening is small.
  • Allow the oil to settle, then reinstall the oil fill cap securely.
  • Check under the bike for leaks, and wipe up any drips.

Start and Check

  • Start the engine and let it idle for a minute. Inspect the drain bolt area for leaks.
  • Shut the engine off and check oil level as per owner manual. Typically, there's a check bolt or sight window (these models often do not have a dipstick). Top up as needed but do not overfill.

Model-Specific Callouts

  • The Honda CR85 Big Wheel is a two-stroke with a separate transmission oil circuit. Do NOT use two-stroke premix oil in the transmission; only use high-quality gear/transmission oil specified for two-stroke bikes.
  • Some owners successfully use ATF Type F for the gearbox, but Honda recommends a dedicated gear oil for consistent clutch performance and longer service life.
  • The drain and fill points are compact, so a small, clean funnel is essential to avoid spills.
  • Check for a stamped oil quantity mark near the fill plug for quick reference.
  • If your CR85RB sees hard use (racing, frequent high RPM), change oil more often for best results—every 5–10 hours is common for mini racers.
  • Always dispose of old oil in accordance with local environmental regulations.

Final Thoughts

  • Changing the oil on your Honda CR85RB Big Wheel is quick but crucial for engine longevity and clutch performance.
  • Always use the correct oil, measure accurately, and take care tightening bolts to factory specification.
  • Refer to your owner's manual for best practices, recommended oil types, and maintenance intervals.

Trust MotoSport.com for all your Honda CR85 Big Wheel maintenance parts, oils, and expert advice to keep you riding strong every season.

Related Shopping Categories

Shop Motor Oil for a 2006 Honda CR85 Big Wheel Dirt Bike.

Shop Oil Filters for a 2006 Honda CR85 Big Wheel Dirt Bike.

Shop Oil Drain Pans for a 2006 Honda CR85 Big Wheel Dirt Bike.

Shop Tools for a 2006 Honda CR85 Big Wheel Dirt Bike.

Shop Oil Fillers and Drain Plugs for a 2006 Honda CR85 Big Wheel 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.