How to Change the Coolant in a 1980 Suzuki RM125
Shop parts for a 1980 Suzuki RM125 Dirt Bike.
The 1980 Suzuki RM125 is an air-cooled, two-stroke motocross legend, but like its siblings from the late seventies and early eighties, cooling system maintenance is vital for reliable performance and long engine life. Follow this step-by-step guide to properly change the coolant and keep your RM125 running at its best.
What You Need
- Engine coolant (50:50 pre-mixed with distilled water is recommended)
- Suitable drain pan
- Metric wrenches
- Funnel
- Rags or paper towels
- Replacement radiator hoses or clamps if needed
Important Note About the 1980 RM125
The 1980 RM125 does not feature a coolant overflow tank. Any drop in coolant level will not be caught or returned to the system, so be sure to check the coolant before every ride and look for leaks or low levels regularly.–
Step-by-Step Coolant Change Process
- Let the engine cool completely.
- Position your bike upright on a stable, level surface using a stand or lift.
- Remove the radiator cap. Never open it while the engine is hot to avoid burns from scalding steam or fluid.–
- Drain the old coolant:
- Locate the lower radiator hose or, if equipped, the dedicated coolant drain bolt on the water pump cover.
- Loosen the hose clamp or drain bolt and direct the coolant into a pan.
- Flush if necessary:
- If the coolant appears dirty or if you are switching coolant types, gently flush the system with distilled water. Compressed air can help remove any remaining fluid.–
- Inspect hoses and clamps for wear or cracks and replace if necessary—this is a common failure point, especially for a motorcycle of this vintage.–
- Close all drain points securely to ensure no leaks. Use the correct tightening torque for hose clamps and bolts.
- Refill with new coolant:
- Use a 50:50 mix of coolant and distilled water unless otherwise specified.
- Slowly pour in coolant until it reaches the base of the radiator neck.
- Bleed air from the system:
- Gently rock the bike side to side and squeeze hoses to coax air bubbles out.
- Start the engine and let it idle briefly with the radiator cap off, watching carefully to top off as needed.
- Replace the radiator cap securely, ensuring that it locks down completely for proper pressurization.–
- Clean up any spilled coolant and properly dispose of the old coolant at a hazardous waste center.
Special Tips for the 1980 RM125
- This machine's coolant level may decrease during riding due to the lack of an overflow tank–frequent checks are strongly recommended.–
- Always use high-quality radiator hoses and clamps to avoid leaks, especially since the original parts may be brittle or degraded over time.–
- Mark the date and hours after every coolant change to maintain a robust maintenance schedule.
Signs of Cooling System Problems
- Persistent low coolant despite no visible leaks–could indicate a failed water pump or internal leak.
- Overheating, hard starting, or coolant loss during rides.
- Corroded or bulging radiator hoses–replace promptly.
Regular coolant changes are essential for your 1980 RM125's health. With preventive care and MotoSport's OEM or upgraded parts, your classic will keep tackling the track season after season.
Related Shopping Categories
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Shop Radiator Hoses for a 1980 Suzuki RM125 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.