How to Change the Oil in a 2005 Honda CR85 Big Wheel: MotoSport.com Exclusive Guide

Shop parts for a 2005 Honda CR85 Big Wheel Dirt Bike.

Keeping your 2005 Honda CR85 Big Wheel running strong means regular maintenance, and one of the most crucial tasks is changing the oil. This guide will walk you through the process, including the specific tools required, step-by-step instructions, and important model-specific tips.

Tools & Supplies Needed

  • Socket wrench set (to fit the drain plug, commonly 12mm or 14mm)
  • Drain pan
  • Funnel (small enough to fit the small oil fill hole)
  • Measuring cup or mixing cup (marked in milliliters or cubic centimeters)
  • Clean rags or paper towels
  • Fresh engine oil – use Pro Honda HP2 2-Stroke Oil (32:1) or an equivalent high-quality 2-stroke oil
  • Torque wrench (recommended to tighten the drain bolt to spec, usually around 21 ft-lb)
  • Rubber gloves (optional but recommended)

Before You Begin

  • Run the engine for a few minutes to warm up the oil. This helps it drain out smoothly and removes more contaminants.
  • Place the bike on a stable, level surface. A dirt bike stand is best.
  • Ensure the area is clean to prevent dirt from getting into the engine while the covers are open.

Step-by-Step Oil Change Procedure

  1. Remove the Oil Drain Plug
    – Position the drain pan under the engine's drain bolt.
    – With the engine off and cool enough to touch, use an appropriate socket to loosen and remove the drain plug.
    – Allow the oil to drain completely. Tilt the bike gently side-to-side to get the last bits of oil out.
    – Check the drain plug for any metal shavings that could indicate internal wear.
  2. Reinstall the Drain Plug
    – Clean the plug and sealing surface.
    – If equipped, replace the crush washer.
    – Hand thread the plug, then torque to 21 ft-lb (do not overtighten as you can strip the aluminum threads)

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  3. Measure and Add New Oil
    – The CR85 requires about 600 mL of transmission oil

    . (Some sources may round this up to 650 mL, but most CR85 guides specify 600 mL for a full change.)
    – Using a measuring/mixing cup, pour in exactly 500 mL first, then add another 100 mL. This precision is crucial for your CR85's health

    .
    – Some funnels may be too large for the fill hole – use a small-tipped funnel to avoid spills

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  4. Replace the Oil Fill Plug
    – Once the correct amount is in, reinstall the fill plug.
    – Wipe away any spills, and check for leaks.
  5. Start and Inspect
    – Start your CR85 and let it idle for a minute.
    – Check below the engine for any leaks.
    – Shut off the bike, let it sit for a moment, and examine the oil level if equipped with a sight window or check bolt.

Model-Specific Call-Outs for the 2005 Honda CR85 Big Wheel

  • The oil fill opening is very small, so a standard funnel may not fit. Use a narrow or flexible funnel to avoid spills

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  • There is no dipstick on the CR85. Always measure oil volume before pouring, and ensure you use 600 mL.
  • The drain plug torque spec is 21 ft-lb. Over-tightening may lead to damage

    .
  • Always use a high-quality two-stroke transmission oil. Pro Honda HP2 (32:1) or a similar oil is recommended by Honda

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  • Double-check for oil leaks because gasket surfaces on older bikes like the 2005 CR85 may begin to deteriorate with age.
  • Let the bike idle briefly after a change to circulate new oil through the gears, then check for any issues.

Tips to Get the Most from Your Oil Change

  • Stick to your chosen oil brand to avoid mixing additives that could react poorly.
  • Change the oil after every few rides or after every race for best clutch and gear longevity with this high-strung 2-stroke.
  • If the bike sees heavy use, inspect and replace the transmission oil more frequently. Clean oil is cheap insurance for your CR85's performance.
  • Keep a log of oil changes to ensure you maintain a regular schedule.

Summary

Changing the oil on your 2005 Honda CR85 Big Wheel is straightforward but demands precision. Use the right tools, measure precisely 600 mL of the correct two-stroke gear oil, and always check for leaks when done. With these steps, your CR85 will stay reliable and race-ready, whether you're hitting the trails or the track.

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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.