Requiring routine maintenance, it’s important to keep an eye on your motorcycle cooling system. Here’s how you can change your coolant.

Up to 65% of a motorcycle’s power is lost due to heat. In order to manage this heat, internal combustion engines in most modern motorcycles are equipped with a cooling system that uses a fluid coolant to move heat from the engine to a radiator where it’s dissipated from the motorcycle.

We don’t pay much attention to our motorcycle’s cooling system until it needs serious attention. However, much like other systems, the cooling system also requires routine maintenance. The general recommendation is that a motorcycle’s cooling system should be drained and flushed every 24 months or 24,000 miles, whichever comes first.

Many coolant variations are available on the market, however, manufacturers will have specific recommendations which should be adhered to in order to maintain the system’s cooling ability.

Coolant does not only allow heat to be removed from the engine, but is also designed to keep the system clear of corrosion and scale, and during winter it prevents the liquid from freezing up and clogging the entire cooling system. Be on the lookout for coolant containing ethylene glycol; this type of coolant is toxic and can be extremely harmful if ingested by humans or pets. Instead, look for a coolant containing propylene glycol which provides the same benefits without the harmful toxins.

You will need some basic hand tools: a drain pan, some rags, a small funnel and, most importantly, a new drain bolt washer (usually copper or aluminium). Do not work on your cooling system until your motorcycle has cooled down completely.

Step one:

Locate the drain bolt. Drain bolts are usually found at the lowest point of the cooling system, so follow the coolant hoses towards the bottom of the engine.

Drain plugs will usually face downwards and have a visible sealing washer. On sports bikes you may need to remove some bits of fairings and panels in order to access the cooling system, so plan your maintenance and complete your coolant flush in conjunction with other maintenance jobs.

Undo the drain bolt with the radiator cap in place and hold your drain pan close to the drain plug. Once completely removed, set the drain plug aside and slowly remove the radiator cap. The coolant will start flowing steadily and you can move the pan down to the floor and allow all the fluid to drain.

Be sure to avoid direct skin contact with the coolant as it could be toxic; once drained, immediately move the old coolant into a sealed container.

Step two:

Locate and remove the coolant reservoir and drain any existing coolant. Clean the reservoir with a bottle brush if necessary. Re-fit your coolant reservoir and ensure that all bolts and hoses are fitted correctly.

Step three:

If you feel the need to flush the entire system, then a simple 50/50 mixture of white vinegar and distilled water will be all you’ll need. Re-fit the drain plug, add the solution and run the engine until the radiator fan comes on. Turn the engine off and allow the system to cool down to room temperature, then drain the solution the same way you did in step one.

Once drained, fill the system again with just distilled water and then drain once again. This will remove any scale that may have built up inside your engine.

Some coolant products may be bought as a concentrate; when diluting these, only use distilled water to avoid adding minerals into the cooling system which may harm the internal parts.

Step four:

Remove the old washer from your drain plug and install a new one. Re-fit the drain plug and use the small funnel to slowly add coolant to the system via the radiator cap.

Some motorcycle radiators have a bleeding screw at the top of the radiator which allows you to get rid of air that may be trapped in the system. You will need to undo this screw and keep filling the radiator until the coolant starts to push out of the bleeding screw.

Alternatively, if your motorcycle does not have a bleeding screw or valve, simply shake the motorcycle to remove any air in the coolant.

Once you’ve successfully topped the coolant you may fit the radiator cap. Don’t forget to fill the coolant reservoir as well to its maximum marker.

While you are down there, you may as well inspect any coolant hoses and clamps for defects or wear. Simply pinch hoses between two fingers to see if it is still soft. Rinse any coolant that may have overflowed with clean water and reassemble any panels where necessary.




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