How to Change the Coolant in a 1979 Kawasaki KX250
Shop parts for a 1979 Kawasaki KX250 Dirt Bike.
Routine coolant changes are critical to maintaining the performance and longevity of your 1979 Kawasaki KX250. This legendary motocross machine relies on a simple but effective liquid cooling system, and fresh coolant safeguards against overheating and corrosion. The steps below will guide you through a complete coolant change, with notes unique to the KX250's design – all courtesy of MotoSport.
What You Need
- Premixed ethylene glycol-based coolant for aluminum radiators (50% coolant & 50% soft water mix recommended)
- Drain pan
- 8mm socket or wrench
- Clean funnel
- Rags for cleanup
Important Precautions
- Never remove the radiator cap or drain coolant from a hot engine. Wait until the bike is fully cool to avoid burns and injuries.
- Coolant is toxic – keep away from children and dispose of old coolant responsibly.
Step-by-Step Coolant Change Process
- Prepare the bike. Place your KX250 upright on a level surface. Ensure the engine is cool before proceeding.
- Remove the radiator cap. Slowly turn the cap to the first stop to release built-up pressure, then remove it completely only after the pressure is relieved.
- Locate the coolant drain bolt. On the right-hand side of the engine, look for the coolant drain bolt below the water pump. Have a drain pan ready beneath this bolt.
- Drain the old coolant. Remove the drain bolt, allowing all coolant to flow into the pan. Gently tilt the bike from side to side for complete drainage. In some cases, there's a second small bleed screw at the cylinder for full flush–open it briefly if equipped.
- Inspect hoses and radiator. Check coolant hoses for cracks, soft spots, or leaks, and visually inspect the radiator for bent fins or blockages. Replace damaged components as needed.
- Replace the drain bolt. Once empty, reinstall the drain bolt and tighten it securely but do not overtighten.
- Add new coolant. Using a funnel, slowly pour in the recommended pre-mixed coolant until it reaches just below the base of the radiator filler neck. The 1979 KX250 uses approximately 1.1 liters (1,100 mL) of coolant.
- Remove air pockets. Briefly rock the bike side-to-side and gently squeeze the hoses to help release trapped air. Leave the radiator cap off.
- Bleed the system. Start the engine and let it idle for one to three minutes. You may see air bubbles rise in the radiator. Shut off the engine and recheck the coolant level, topping off if necessary.
- Secure the radiator cap. Once the level is stable and no more air bubbles are visible, reinstall the cap fully.
- Clean up. Wipe away any spills and safely dispose of the used coolant.
Model-Specific Notes for the 1979 Kawasaki KX250
- This generation uses a simple single radiator system with straightforward accessibility–great for home mechanics.
- The cooling system is low-capacity at only 1.1 liters, so use care to avoid overfilling or spillage.
- Ensure your replacement coolant is compatible with aluminum engines and radiators, as the 1979 KX250's radiator and cases are susceptible to corrosion from incompatible coolants.
- Inspect the radiator cap. Weak pressure relief (should hold 14–18 psi) can allow overheating.
When to Change the Coolant
- Every 12 months or after every 40 hours of riding for best protection.
- If the coolant appears rusty, dirty, or the system is losing fluid with no obvious leaks, change it sooner.
Keep your vintage KX250 running at its best by making coolant service a part of your regular routine. If you need seals, hoses, radiators, or any service parts, shop parts for a 1979 Kawasaki KX250 Dirt Bike. and keep your legend on the track for seasons to come.
Related Shopping Categories
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Shop Radiator Hoses for a 1979 Kawasaki KX250 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.