How to Change the Coolant in a 2007 Honda CR125: MotoSport Proprietary Guide

Shop parts for a 2007 Honda CR125 Dirt Bike.

Regular coolant changes are essential for your 2007 Honda CR125's long-term engine health – especially given its high-revving two-stroke design. Unlike street bikes, the CR125 is built for off-road performance, which means its coolant system encounters intense thermal cycling and must be serviced to maintain peak power. Here's a MotoSport step-by-step to ensure your cooling system stays in optimum condition:

Preparation — What You Need

  • Compatible dirt bike coolant (check for ethylene glycol or a race-prepped coolant, never just tap water)
  • Drain pan
  • 10mm wrench (for drain bolt)
  • Shop towels
  • Copper washer, if replacing
  • Funnel
  • Protective gloves

Step 1: Safety First

  • Let the bike cool completely. Never open the radiator cap when hot – hot coolant can spray and cause burns.
  • Position the bike upright in a well-ventilated space.

Step 2: Drain Old Coolant

  • Remove the radiator cap to release any pressure. This lets coolant flow out easily.
  • Locate the coolant drain bolt at the right side of the cylinder, usually near the water pump cover. Place a drain pan below.
  • Remove the bolt and washer. Coolant will flow out rapidly – be prepared with towels.
  • Once draining slows, slowly kick the starter a couple of times (ignition OFF) to help clear residual coolant from passages.

Step 3: Flush (Optional, Recommended)

  • If dirt or sediment is present, flush the radiator and system with clean distilled water before refilling. Repeat the drain procedure to remove rinse water.

Step 4: Reinstall Drain Bolt

  • Inspect and replace the copper washer if necessary.
  • Tighten the drain bolt snugly

Step 5: Refill with New Coolant

  • Slowly add the correct coolant using a funnel until the radiator is filled to the base of the cap neck. Allow air bubbles to escape while filling.
  • Replace radiator cap securely – turn it until it clicks twice for proper lock.

Step 6: Bleed System and Final Top-Off

  • Start the bike and let it idle a few minutes with the radiator cap ON. This circulates coolant and helps purge air from the system.
  • Turn off the engine, let it cool, and then check the coolant level again. Top off if needed – do not overfill past the neck.

What 2007 Honda CR125 Owners Should Know

  • High RPM use: The CR125's two-stroke engine generates rapid heat cycling, making coolant quality and level a critical maintenance point for preventing overheating and seizure.
  • No overflow bottle: This model dumps excess coolant if overfilled – always fill slowly and check the level after cooling post-ride.
  • Aluminum cooling system: Use only coolant safe for aluminum and magnesium parts.
  • Check before every ride: Coolant level inspection is part of pre-ride checks for this bike, as outlined in the owner's manual.

Pro Tips from MotoSport

  • Change coolant every 40–50 hours of run time or at least once a year, more frequently in extreme conditions.
  • After a coolant change, always ride gently and monitor engine temps during the first outing.
  • Dirty coolant or debris may indicate a failing water pump seal or internal corrosion – consider service if you see issues.

Your 2007 Honda CR125 is legendary for its lightweight power and nimble handling. Keep the cooling system fresh, and the bike will reward you with top performance & reliability season after season.

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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.