How to Change the Oil in a 1995 Cobra BM50

Shop parts for a 1995 Cobra BM50 Dirt Bike.

Changing the oil in your 1995 Cobra BM50 is a crucial maintenance task to keep your bike running smoothly and extend engine life. This detailed guide, proprietary to MotoSport.com, covers all the tools you'll need, step-by-step instructions, and model-specific tips for your Cobra BM50 dirt bike.

Tools and Materials Needed

  • Socket wrench set (including a 17mm socket for common drain plugs)
  • Oil drain pan
  • Funnel
  • Clean rags or paper towels
  • New engine oil (refer to manufacturer's recommendation; high-quality 2T oil is typically used in premix for this model)
  • New oil filter (if your model has a separate filter, check your manual)
  • Gloves (to keep hands clean and protected)
  • Torque wrench (for reinstalling drain bolt to spec)
  • Wide-mouth flat screwdriver (optional, for stubborn drain or fill plugs)

Preparation

  • Warm up your engine briefly.– Oil flows out more easily when slightly warm. Idle the bike for 2–3 minutes, then shut off.
  • Stand the bike securely on a stable surface using a stand. This ensures a complete drain and prevents accidents.

Step-by-Step Instructions

  1. Locate the Drain Plug:–
    • The oil drain plug is typically found on the right side of the engine, on the clutch cover, near the brake lever. Consult your model's manual if unsure.
  2. Drain the Oil:–
    • Place the drain pan underneath the bike, directly under the drain plug.
    • Using your 17mm socket, carefully remove the drain plug. (Gloves help avoid hot oil contact.)
    • Allow all oil to fully drain. This may take several minutes. Tipping the bike slightly side to side (while secure) helps remove old oil.
  3. Inspect and Clean:–
    • Check the condition of the drain plug and gasket. Clean off any metal shavings or sludge.
    • Replace the washer or gasket if it shows wear or cracking.
  4. Change the Oil Filter (if equipped):–
    • Some Cobra models are oil-injected or use direct premix with no standard spin-on filter; consult your manual to see if a filter is present.
    • If your BM50 has a replaceable filter, remove it and let residual oil drain. Lightly oil the seal of the new filter and install it finger-tight, then snug per spec.
  5. Reinstall Drain Plug:–
    • Thread the cleaned drain plug by hand to avoid cross-threading. Tighten to manufacturer's specified torque (do not overtighten).
  6. Refill with Oil:–
    • Insert a funnel into the oil fill port. Add the recommended amount of high-quality 2-stroke engine oil for the next premix, or if using oil injection, fill the specific reservoir for injection oil.
    • For premix: Use Motul 800 T2 premix or equivalent, mixed at 50:1 (50ml oil per 1.3 gallons of fuel or 38ml oil per 1 gallon of fuel) per manufacturer recommendations for standard riding. For break-in, use 32:1 mix if not using Motul 800 T2.
    • Check your owner's manual for any specific ratio changes or oil recommendations.
  7. Check Oil Level:–
    • With the bike level, check for correct oil level according to your engine's sight glass, dipstick, or premix ratio if applicable.
  8. Start and Inspect:–
    • Start the bike and let it idle for 1–2 minutes. Shut off and inspect for leaks at the drain plug and (if applicable) oil filter.
    • Recheck oil level and add more if needed.
    • Dispose of old oil responsibly at a recycling center.

1995 Cobra BM50 Specific Call-Outs

  • Fuel/Oil Mix:– This model, like many small-displacement Cobras, is intended for premix operation and does not have a four-stroke-like engine oil sump. Always use fresh, high-octane pump gas and mix with quality two-stroke oil as specified (50:1 for Motul 800 T2, 32:1 for break-in with other oils).
  • Break-in Procedures:– Following proper oil mixing ratios during break-in is crucial for long engine life. See the user manual for break-in details and avoid prolonged high RPM or excessive clutch abuse during this period.
  • Cleanliness is Key:– The small tolerances in the BM50's engine mean clean oil and fuel are critical. Always use clean mixing containers and fresh oil.
  • No Standard Oil Filter:– Most BM50s do not have a separate oil filter; oil changes pertain to gearbox oil (if present) or premix ratios. Check manual for model year updates.
  • Gearbox Oil Change:– If your BM50 is equipped with a separate gearbox oil (common for clutch cover-type transmissions), be sure to use the correct volume (refer to the service manual, generally a small volume around 200–250ml of synthetic gear oil).

Additional Tips

  • Keep a maintenance log for your oil changes, ratios used, and hours ridden.
  • Periodically check for leaks after every ride as gasket and seals can age.
  • Do not overfill–more is not better, especially with crankcase and transmission capacities.
  • Use only manufacturer-recommended oils and adhere to mixing ratios to avoid engine wear or damage.

By following these steps and adhering to Cobra's recommendations, you'll keep your 1995 BM50 running strong. For genuine Cobra parts and race-grade oils, trust MotoSport.com—your source for all things dirt bike performance and upkeep.

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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.