Cooling System

Cooling System

You’ll find aluminum radiators on all high performance dirt bikes built today. Due to weight and size issues related with dirt bikes these aluminum radiators are placed in tight areas and at the front part of the bike where they will get hammered with rocks, sticks, and crashes. If your radiators get damaged to the point of it leaking coolant then you race or trail ride has ended. Take care of your cooling system by performing proper maintenance and invest in protection (radiator braces) for the radiators.

Cooling System Cleaning & Inspection

You should flush the cooling system on your dirt bike once a year. Corrosion, debris, or other waste can clog the tiny passages inside the radiator. Before draining the cooling system add a few ounces of an aluminum radiator flushing fluid. Most all auto parts will care these flushing products. Next run the engine for 10-15 minutes (maybe ride the bike to prevent overheating) then drain the cooling system. Contact your local auto parts store and see if they have a recycling drum for used coolant. Once you have drained all the coolant remove the water pump cover and check for debris or even corrosion. Grab the water impeller and see if there’s any movement up and down. Any movement would indicate the water pump shaft bearings are worn. In most cases if the bearings are worn then the seals are worn and leaking water in to the crank case. The best repair is to replace the water pump shaft (usually grooved from seals), bearings, and seals as a set because the parts are not very expensive.

Filling & Bleeding Tips

Some bikes have a bleed bolt on top of the cylinder head that is used to purge air out of the engines cooling passages and some are self bleeding by design. If the air is not bleed completely from the system it can prevent the coolant from circulating and the engine temperature will rise until the radiator caps releases and coolant is spilled out on the ground (boil over). Remove the radiator cap, fill the system to the top of the radiator, loosen the bleed bolt on top of the cylinder head until a solid steady stream of coolant is flowing out and then tighten bleed bolt. The other radiator on the bike is going to be self purging of air, it is being filled from the bottom and pushes all the air to the top where there’s a connection hose between both radiators. Next top off the radiator and install the cap, run the engine for 5-10 minutes and then check the coolant level again. Caution: Make sure you let the engine cool down before removing the radiator cap, hot coolant can burn your hand.

Radiator Protection

Radiators are very expensive to replace so protect them. There are aftermarket companies that make radiator braces. These braces help keep the radiators from bending or being crushed due to a crash. You can also remove the factory plastic louvers and replace them with an aftermarket aluminum screen which help protect the radiator core from rocks, sticks etc. Remember that the factory louvers help channel air flow in to the radiators core for proper cooling, so removing them can cause some overheating issue in certain riding condition.

Cooling Improvement Tips

You can improve the efficiency of the cooling system by switching radiator cap marked with 1.6 which will raise the pop off pressure and increase boiling point. You will find some aftermarket companies that offer improved water impellers and housing, and even larger radiators to help improve cooling efficiency. There are special coolants made by Engine Ice, Spectro, etc. that can be used to help improve cooling.