Radiators are fragile things. If you ride long enough, at some stage you’re going to damage one, either in a crash, or by running a stick past the radiator louvres and into the core. So, if your last ride ended in a cloud of steam and boiling water, here’s how to replace the thing. Radiator cores can be repaired, but the repair will always be a potential source of unreliability. Whether you repair or replace depends entirely on how seriously you take your riding or racing.

Diagnosis. This is easy. If you are enveloped by steam during a ride or after a crash, you’ve probably damaged the radiator, or one of the hoses. If it’s just a hose you can generally MacGyver the damage enough to get home. If the core is damaged, start pushing or unpack the tow strap and get a tow home.

Step one. Seat off, tank off. Now, there will still be some coolant left in the system which you have to remove. At the bottom of the water pump, on the right hand side of the motor is a drain plug. Remove the plug, while holding a bucket underneath to catch the coolant. When all the coolant has drained, replace the drain plug, using the torque figure in your manual. Coolant is toxic, so keep it out of your mouth, off your hands and dispose of it sensibly.


Step two. Remove the radiator louvre, either by popping the lugs out of the locating holes or by unbolting it. Find the securing bolts (normally two) and remove them, letting the radiator hang from its hoses. If there is a fan attached to the radiator, disconnect it at the connector block. Loosen the hose clamps securing the hoses to the radiator then pull and twist the radiator off the hoses. If the hoses are stuck, carefully slide a thin screwdriver between the pipe and the hose and prise it off.  Don’t damage the end of the pipe, hopefully you will be sending this radiator to your dealer for repair and keeping it in your pit box. If you have a radiator guard, disassemble it now and remove it from the radiator.

Step three. If there is a fan attached, remove it by either unbolting it or by very carefully drilling out the rivets. If you have a radiator guard, the chances are that this will be out of shape. You will have to panel beat the thing with whatever tools you have to get it straight and not rubbing against the soft aluminium of the radiator at any point. Usually a vice and a selection of hammers and mallets will be needed. Once you’re happy with the guard, re-install the fan, and re-assemble the guard around the radiator.

Step four. Re-install the radiator. Slide the hoses onto the pipes, then line up the radiator and replace the securing screws. Now you can tighten the hose clamps. These are very easy to strip, so tighten them with a screwdriver, rather than with a socket and T bar which can apply a little too much torque. Replace the louvres. On a KTM it is always a good idea to cable-tie the louvre top and bottom to the radiator guard. Replace the fan wire, and route the wire out of the way of the fuel tank mounts.

Finally. Fill the radiator with Motul Mocool or Motul Motocool, and replace the seat and tank. The final step is to test. Start the bike and let it idle until it’s hot. Check all the hose-clamp joints for leaks and tighten where necessary. You’re done.


Unclipping Louvre


Loosening hose clamps


Panel beating radiator guard


Tightening hose clamp









Louvre cable tied to guard

Motul coolant_1








Ride safe

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