How to Change the Coolant in a 2016 Cobra CX50JR

Shop parts for a 2016 Cobra CX50JR Dirt Bike.

Changing the coolant in your 2016 Cobra CX50JR is a vital maintenance task that keeps your two-stroke race bike running cool – and ensures long engine life under intense conditions. This youth race bike comes with a high-revving engine and is engineered for top performance, which means the cooling system must always work at peak efficiency.

Tools & Supplies Needed

  • Fresh premixed coolant (or concentrate and distilled water; never use tap water)
  • Drain pan
  • 4mm & 3mm hex keys
  • Flathead screwdriver
  • Shop rags
  • Protective gloves/safety glasses

Step-by-Step Coolant Change Guide

  1. Preparation: Ensure the bike is cold and on a stable stand. Remove the shrouds or bodywork if needed for access to the radiator cap and hoses.
  2. Remove the Radiator Cap: Slowly unscrew the radiator cap to relieve any pressure. Place your drain pan below the water pump.
  3. Drain the Old Coolant: Locate the cooling system drain bolt (typically on or near the water pump). Remove it with the correct hex key, allowing coolant to flow into the pan. Some spillage is normal – use rags to catch drips. Inspect the drained coolant for signs of oil or abnormal discoloration. These can indicate internal issues; consult a technician if spotted.
  4. Flush (Recommended if Maintenance Is Overdue): Replace the drain plug and fill the radiator with distilled water. Run the engine briefly (cap off, carefully.) to circulate water, then drain again. If flushing, you may need to repeat. Never use harsh chemicals – only distilled water is safe.
  5. Refill with Coolant: Tighten the drain bolt with a fresh sealing washer if needed. Pour in the new coolant slowly, up to the base of the filler neck. Squeeze hoses and gently rock the bike to help air escape.
  6. Burp the Cooling System: With the bike on a level surface, start the engine (cap off). Gently rev and rock the frame to free trapped air. Watch for the coolant level dropping as air escapes. Add more coolant if needed and stop the engine after a minute – before it gets hot enough to bubble over.
  7. Final Steps: Reinstall the radiator cap, then fill the reservoir tank to the recommended line if your CX50JR is equipped with one. Run the engine up to operating temperature, shut off, and let cool. Recheck and top off the coolant after the first ride. Always dispose of old coolant safely.

2016 Cobra CX50JR Notes & Pro Tips

  • The CX50JR uses a high-performance cooling system designed for racing – always use coolants approved for aluminum radiators and magnesium cases.
  • Watch for leaks after coolant changes; this can indicate aging gaskets or hose clamps that may need tightening or replacement.
  • Cobra designs the CX50JR's water pump for quick serviceability – if you notice any impeller or shaft noise, inspect and service as needed with the manufacturer-specific tools mentioned in the shop manual.
  • Coolant should be changed at least once per season, or more frequently if the bike is raced hard or in muddy/sandy conditions.

Keep your Cobra CX50JR race-ready with these steps, and you’ll help guarantee peak performance lap after lap.

Related Shopping Categories

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Shop Radiator Hoses for a 2016 Cobra CX50JR 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.