How to Change the Coolant in a 1989 Suzuki RM125
Shop parts for a 1989 Suzuki RM125 Dirt Bike.
Properly maintaining the cooling system of your 1989 Suzuki RM125 is essential for peak performance and long engine life, especially since this model is known for hard charging two-stroke power and high-rev riding. Below you will find a step-by-step guide customized for your RM125, so you can flush out old coolant, prevent overheating, and keep your bike running at its best through every moto.
Why Changing Coolant Matters for Your RM125
The RM125 relies on a liquid-cooled system that, if neglected, can allow mineral deposits and old coolant to clog passages or cause the engine to run hot. Especially with older models like 1989, periodic coolant changes prevent corrosion in the radiators and water pump, preserving performance.
What You Need
- Fresh, high-quality motorcycle coolant compatible with aluminum radiators
- 8mm socket or wrench
- Drain pan or suitable container
- Distilled water (for flushing)
- Clean rags
- Funnel
- Protective gloves and eyewear
Step-by-Step Coolant Drain & Replacement
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Allow the bike to fully cool.
Never open the radiator cap on a hot engine–the pressurized system can spray hot coolant. Ensure the RM125 is on level ground. -
Remove the radiator cap.
Loosen and remove the cap (located on top of the left radiator) to relieve any pressure and prepare for draining. -
Locate and remove the water pump drain bolt.
Find the 8mm drain bolt at the bottom of the water pump cover on the right side of the engine. Place your drain pan underneath, then remove the bolt and allow all coolant to drain out. Tip the bike side-to-side gently to help clear remaining fluid. -
Flush the system (recommended).
Pour distilled water into the radiator until it comes out clean from the drain. This step helps remove old coolant and any potential buildup. -
Reinstall the drain bolt.
Make sure the crush washer is still in good shape, then hand-thread the bolt and tighten securely–do not overtighten to prevent stripping the threads. -
Add new coolant.
Use a funnel to slowly pour fresh, premixed coolant into the radiator until full. Stop occasionally and tap the hoses to help release trapped air. Fill until coolant reaches just below the base of the fill neck. -
Bleed air from the system.
Squeeze the radiator hoses or briefly operate the kickstarter (with the ignition off) to cycle out air, then top off coolant if the level drops. -
Replace the radiator cap securely.
Ensure the cap seats properly and the tab is aligned past its locking point. -
Clean up and check for leaks.
Wipe up any spills and inspect around the water pump and radiators as you start and warm up the bike.
Special Considerations for the 1989 RM125
- The 1989 RM125's radiators are aluminum and can corrode with improper coolant or tap water–always use distilled water for flushing and a silicate-free, aluminum-safe coolant.
- Pay close attention to the water pump cover–scratches or nicks from prior maintenance may cause slow leaks.
- If you ride in muddy or sandy conditions, inspect the radiator fins for debris and use a gentle stream of water to keep them clear for maximum cooling performance.
Disposal
Dispose of old coolant responsibly. Many automotive stores and recycling centers accept used coolant. Never pour it down drains or onto the ground.
Final Tips
- Replace coolant at least once per year or after any overheat episode.
- Check coolant levels before every ride for peace of mind.
Related Shopping Categories
Shop Radiators for a 1989 Suzuki RM125 Dirt Bike.
Shop Coolant for a 1989 Suzuki RM125 Dirt Bike.
Shop Temperature Sensors for a 1989 Suzuki RM125 Dirt Bike.
Shop Tools for a 1989 Suzuki RM125 Dirt Bike.
Shop Radiator Hoses for a 1989 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.