KawasakiGPz900r overheating problems


Gpz motor

I have had a few questions recently about the old KawasakiGPz900r overheating and getting a bit hot under the collar. This has been a long standing gripe of GPz owners. I have dealt with this issue a number of times over the years with a good degree of success.

The first thing to do is go through the basics, if the bike has not had a coolant change and coolant system flush for as long as you can remember this is where to start. You can do this at home with a garden tap and some basic tools.

You need to remove the tank and get to the radiator cap and the thermostat. Its a good idea to remove the thermostat and just replace it as they are cheap to buy and a bit of insurance as you don’t want the old one to fail!

Now you can put the hose in the radiator and flush the whole cooling system out. Run the hose until the water rust out clear and free of dirt and rust and other gunk and muck that has built up over the decades.

While you are flushing you can check all of the hoses and fittings for corrosion and damage and spongy rubber which will need replacement. Also have a good look at the radiator for any damage to the fins and tubes which may reduce the cooling ability.

New alloy radiators are now available for these old bikes and have a much better ability to dissipate heat than the old ones.  May be a good upgrade if the budget will allow.Gpz rad

So if everything is ok and you have done all the above it’s time to get some new coolant and mix it in the correct ratio depending on the brand that you bought. Fill up the coolant system and start it up. A new radiator cap is also a good idea as the seals don’t last forever!

Now you need to bleed the system through the small bleed nipple on the thermostat housing. As the bike warms up just open the bleeder every few minutes and get rid of the excess air in the system. Eventually the water will run out clear with no air in  a solid stream and you will be done. Keep an eye on the temperature gauge while this is happening and stop if it gets hot, wait until it cools down add more coolant and start again.

Check the coolant system for any leaks, make sure all hoses and fittings are tight and you are nearly ready to rock and roll.

The other part of the cooling system is the electric fan, this can also have issues and needs to be in top condition and working properly to keep things cool.

Due to the way that kawasaki designed the fan circuit from new it’s common that the fan cuts in quite late and the bike will get hot in traffic or prolonged slow speed riding. An easy fix is to install a manual switch in the fan circuit to turn on the fan when needed. The switch can be mounted next to the ignition switch in the plastic cover.

An other way of doing it is to replace the temperature sender with an adjustable fan control switch. This is a bit more complicated and you need some understanding f how the Kawasaki system works to get this operating properly.

Now that you have checked your cooling system and all the parts are in good condition with a new thermostat and radiator cap and a good flush the old kwaka should keep its cool.

Keep on riding!




If you want to learn more about your bike get the manual!


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