How to Change the Oil in a 1998 Honda CR125: Step-by-Step Guide

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Changing the oil in your 1998 Honda CR125 is an essential part of routine maintenance and helps ensure maximum performance and longevity from your two-stroke dirt bike. This process, though simple, must be performed correctly to avoid potential engine or transmission issues. Below you will find a comprehensive guide specific to your make and model, including necessary tools, step-by-step instructions, and key tips exclusively for the 1998 CR125.

Tools and Materials You'll Need

  • 17mm socket (or possibly 14mm, confirm with your bike as some year variations have either size) and ratchet
  • Drain pan (oil catch pan)
  • Funnel
  • Clean rags or shop towels
  • Replacement oil (Honda recommends quality transmission oil or a high-quality 10W-30 or 10W-40 non-friction-modified oil; some riders use Shell RotellaT 15W-40 with proven success)
  • New aluminum washer for the drain bolt
  • Torque wrench (optional but recommended)
  • Stand or triangle stand for your bike
  • Gloves (optional for cleanliness)

Important Call-outs for the 1998 Honda CR125

  • This bike uses a wet clutch transmission oil system, so you are changing the gearbox/clutch oil, not the premix for combustion.
  • The 1998 CR125 drain plug is typically a 17mm bolt located at the bottom of the engine. (Some references mention a 14mm bolt; always confirm visually before starting.)
  • The *fill hole* is next to the kick starter, and there is a small bolt in the clutch cover that serves as the oil level check bolt.
  • The correct oil quantity is about 600cc to 650cc (approximately 0.62 to 0.69 US quarts or 20–22 ounces). Fill until oil seeps from the level check hole–do not overfill.
  • Always use a new washer on the drain plug to guard against leaks.

Step-by-Step Oil Change Instructions

  1. Warm Up the Engine
    • Start and run your bike for 1–2 minutes. This helps the oil heat up, thinning it so it drains out more easily and removes more contaminants.
  2. Position the Bike and Tools
    • Place your bike on a stable stand–either a triangle or center stand.
    • Place the oil drain pan directly beneath the engine drain bolt.
  3. Remove the Drain Plug
    • Use your 17mm socket (or 14mm if applicable) to loosen the drain plug at the very bottom of your engine.
    • Be cautious–the oil will be hot.
    • Let all the oil drain completely into the pan. Inspect the old washer on the drain bolt and replace with a new one.
  4. Remove the Oil Level Check Bolt
    • This is a small bolt located on the right side engine cover (outer clutch cover). Removing it allows air to enter and ensures an accurate fill later.
  5. Reinstall the Drain Plug
    • Install the drain bolt with a new washer. Tighten securely but avoid overtightening (spec torque is around 10–12 ft-lbs).
    • Wipe any excess oil from the area using a clean rag.
  6. Add New Oil
    • Unscrew the oil fill cap (located next to the kickstarter).
    • Using a funnel, add oil gradually–about 600cc to 650cc–and keep checking the level at the oil level check hole.
    • Stop adding once you see oil just start to seep out of the check hole. This indicates the transmission is full.
    • Reinstall and tighten the check bolt after oil seeps out, then screw the oil fill cap back on.
  7. Clean Up and Check for Leaks
    • Start the bike and let it run for 30–60 seconds. Shut it off and inspect around the drain plug for any leaks. Tighten slightly if needed.
    • Dispose of old oil properly at a recycling center or automotive shop accepting used oil.

Proprietary MotoSport.com Tips for the 1998 Honda CR125

  • Always warm the bike first for best results and a cleaner change.
  • Avoid automotive engine oils that contain friction modifiers (these can harm the wet clutch).
  • Inspect your oil for any gray tint or metallic particles, which suggest clutch or gear wear. Small amounts are normal due to clutch fibers; excessive particles may require closer inspection.
  • Make it a habit to replace the crush washer with every oil change to prevent leaks.
  • Change oil every 5–10 hours of riding, or after every few rides—more frequently for racing or riding in dirty conditions.
  • Record the date and hours at each oil change for consistent maintenance tracking.

Conclusion

Changing the oil on your 1998 Honda CR125 is straightforward: warm up the engine, drain the old oil, replace the washer, fill up with the correct oil to the proper level, and always inspect for leaks. Staying proactive with oil changes is a vital step to keeping your CR125 performing at its best on the track and trail.

Article proprietary to MotoSport.com. For all your maintenance parts and oil needs, visit MotoSport.com’s exclusive dirt bike service selection.

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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.