Motorcycle radiators like the types used on dirt bikes are made from metal alloy or plastic. Some dirt bikes have a pair of radiators for added cooling efficiency with larger engines. Even with a radiator guard, plastic dirt bike radiators can get damaged. Over time, metal radiator cores develop problems resulting from rust or corrosion that clogs the flow of coolant. Repairing a dirt bike radiator is done using a few basic hand tools and a radiator repair kit.
1) Allow the dirt bike engine and radiator to cool completely. Use a metric wrench to open the petcock and drain the radiator coolant. Use a metric socket and ratchet to remove the bolts that hold the radiator guard to the mounts on the bike frame. Remove the guard and set it aside.
2) Use a screwdriver to loosen the clamps on the upper and lower radiator hoses. Pull the hoses off the ports. Remove the bolts that hold the radiator in place and remove the radiator from the bike. Place the radiator on a workbench.
3) Clean the damaged section of a plastic radiator with a non-residue spray cleaner. Remove any oil, dirt or debris from the area. Use medium grit sandpaper and prep an area a few inches larger than the damaged section.
4) Refer to the instructions on the radiator repair kit and mix a batch of the two-part epoxy resin patch. Use the provided spreader tool and apply a uniform layer of the resin over the damaged area.
5) Apply one or more of the provided strips of fiberglass material onto the resin as needed to cover the damaged area. Smooth the material with the provided brush until the resin is fully absorbed into the fiberglass. Allow the patch to dry for four hours.
6) Take a metal radiator to a radiator repair shop and have it cored and soldered. Paint the repaired radiators with a high-heat spray-on primer. Allow the primer to dry for at least three hours. Install the repaired radiator on the dirt bike. Connect the hoses and reattach the guard. Fill the radiator with the recommended coolant.
* Some models have a heat sensor that must be removed and reattached later.
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