How to change the coolant on your motorcycle

And just like other systems on your motorcycle, it needs periodic attention. Many riders delay coolant changes or neglect them altogether, and I'm not sure why, because changing the coolant is as easy as an oil change and is critical to keeping the cooling system in tip-top shape.

 

When should I change the coolant on a liquid-cooled motorcycle?

As a general rule, the coolant on your liquid-cooled motorcycle should be changed every two years or 24.000 miles, even if it looks good. Cloudy or brownish coolant should always be drained and replaced. Check your owner's manual for your motorcycle's specific coolant change interval.

You may also need to change your bike's coolant for a day on the track. Trackday organizations may require you to drain the coolant and replace it with distilled water in case the system runs low along the way. These organizations may allow other additives, such as Water Wetter, or they may allow a propylene glycol-based coolant, such as Engine Ice, for example, but not an ethylene glycol-based coolant. And they may have different requirements for advanced levels but not for beginner levels, so ask first and make sure you comply with all track rules before arriving.

When should I change the choke on an air-cooled motorcycle?

Get out of here.

What's in your motorcycle's coolant and why does it need to be changed?

Most liquid-cooled motorcycles use a 50/50 mix of water and antifreeze to wick engine heat through the radiators. Water is a fantastic choice for conducting heat. However, good old H20 becomes a liability once temperatures drop below freezing. Antifreeze takes care of the ice problem, and different formulations can offer other benefits, such as increased corrosion resistance or a higher boiling point. You'll usually see ethylene glycol (toxic) or propylene glycol (non-toxic, but still worth having) in standard antifreeze.

Over time, different coolant ingredients can break down. Coolant can also get very dirty, and reduced cooling performance can directly affect the health of your motorcycle.

What coolant should I use? Can you use car coolant in a motorcycle?

Open your motorcycle's manual and see what coolant it requires. The manual will list coolant specifications that you can compare to the wide range of coolants available today. Do a little research to see what other riders are using for your particular model and don't get too caught up in choosing the perfect, best-performing coolant. Just make sure you match the specs in the manual.

As for “car coolant”, it depends. I assume you're talking about the standard Prestone green stuff etc. If it meets all the specs in your manual, sure, you can use automotive green stuff, avoiding the silicates if you can. Only buy the right stuff and don't risk your engine. On a related note, don't assume that the green coolant in your motorcycle is the same as the green coolant used in your car. Modern refrigerants come in a rainbow of colors that don't necessarily mean the same thing from one formulation to another.

What tools and supplies do I need to change my motorcycle's coolant?

Not so much! Here's the full list of what I'm using today.

• Service Manual (for coolant capacity and model-specific instructions)
• refrigerant. The FZR requires 2,2 gallons of 50/50 ethylene glycol coolant with aluminum engine corrosion inhibitors. I am using Zerex 675130 Asian Vehicle Antifreeze.
• One gallon of distilled water for rinsing or mixing with concentrate if necessary. Zerex is prediluted.
• New drain bolt anti-crush washer
• Basic hand tools for removing plastic and parts
• Dish drainer to catch the coolant and a few rags just in case
• Rubber mat. Spilled coolant can create a mess on driveways, garage floors and sidewalks.
• Small funnel

How to change the coolant on your motorcycle

Make sure your bike is cold before starting. Do not unscrew the radiator cap while the motorcycle is still hot! You will need access to the radiator cap, water pump, and fuel tank. Get out your tools and dig.

Place the drain pan under the water pump. Not sure where your pump is? Just follow the pipes. Locate the coolant drain plug, typically a small bolt in a low spot on the water pump cover, and remove it.

The coolant will flow out. Unscrew the radiator cap and the flow should increase noticeably.

While you wait for the old coolant to drain, check the hoses for cracks or stiffness, then prepare new coolant. Read your bottle carefully: pre-diluted coolant can go straight in, but otherwise you'll have to mix the concentrate with distilled water. Avoid the temptation to use regular tap water, as minerals and other junk may not work well with your cooling system.

With the coolant mostly drained, raise the bike and tilt it from side to side to shake out any remaining coolant. I usually fill the system with plain distilled water (hey, it's cheap) and drain it again, and I always see a little color in the stream as it pours into the pan. This is especially important if you are changing refrigerant types, as you should never mix different refrigerants. Say it with me: never mix different coolants.

If you're replacing cooling system components, like the thermostat or hoses, now is the time to do it. The FZR hoses are now 25 years old, so I'm replacing them with a set of new silicone hoses from AS3 Performance.

 

The last flush job required is the tank tank. Usually a clear plastic container hidden near the engine or in the tail, you'll want to remove any old coolant stuck inside. If you see any nasty sediment built up on the walls, remove the tank from the bike, connect the hose fittings and pour in some isopropyl alcohol with a tablespoon of table salt. Vigorous shaking will remove most stains and debris. Rinse with distilled water before reinstalling.

 

Install your new drain bolt pinch washer and discard the old one. Make sure the old washer is not stuck to the bolt. Check the torque specifications of the water pump drain plug and reinstall it. My FZR only wants five foot pounds here, so this is no time for gorilla strength or cheater bars.

Rinsing the motorcycle coolant and radiator

If you want to remove any rust or scale from the system before adding new coolant, it's probably best to avoid harsh chemicals. Instead, try a 50/50 mixture of vinegar and distilled water. Run the motorcycle until the radiator fan turns on, then turn the motorcycle off and let it cool to room temperature. Drain the vinegar/distilled water mixture, rinse the system again with distilled water only, and drain once more. Flushing is recommended for neglected or unknown cooling systems. Otherwise, it's reasonably safe to skip it.

 

Adding coolant

Finally, you can pour that fresh coolant into your cooling system's filler neck through a funnel. Reduce spills by slowly pouring into the funnel, then pausing to listen to the gurgling sound of the filling system. Start pouring again when the sound stops. Tighten the coolant hoses and rock the motorcycle from side to side to eliminate air bubbles.

Your motorcycle may require less than its full capacity when you first fill it up, but don't worry. Once the system is full, leave the radiator cap open and run the motorcycle for a minute. A few quick spins should shake out any remaining air bubbles. Turn off the motorcycle, recheck the levels and add coolant if necessary. Fill the tank to the full line (mine is on the back), put the radiator cap on and you're ready to ride! I typically double check the coolant level in the reservoir reservoir after the bike's next trip just to make sure everything is copacetic.

How to dispose of motorcycle coolant?

Refrigerants should never be poured into the ground or down the drain, even if they claim to be environmentally friendly. Don't leave open containers of coolant lying around, especially if it's ethylene glycol and especially if you have pets. Dogs seem to like the taste of coolant, for whatever reason. Save Mother Earth and Fido by bottling up your old coolant and dropping it off at your local auto parts store or recycling program.

⚠️ Legal Notice – Important Product Declaration

This product is not certified, approved, or homologated for use on public roads or highways in any country. It is intended for off-road use only, including closed-course racing, sports competition, or private testing . Installation and use of this product on vehicles operating on public roads is strictly prohibited and may violate traffic laws, emissions regulations, or roadworthiness inspection requirements.

By purchasing this product, the customer acknowledges and accepts the following:

• The product is sold “as is” for sports or off-road use only.
• It is not approved for road circulation and must not be used on public roads under any circumstances.
• Seller assumes no responsibility for improper, illegal or unauthorized use of this product.
• The customer is solely responsible for ensuring that the installation and use of the product complies with local laws and regulations.
• Use of this product outside of its intended use may affect your vehicle warranty and insurance coverage.

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