Oil cooler cooling system is a cooling system engine that serves to reduce the temperature of lubricating oil contained in the cylinder. The oil cooler system aims to keep the oil temperatures stable in order to keep the maximum lubrication system. This temperature measurement aims to determine the difference between engine temperature before and after the installation of oil cooler system on Honda Supra X 100 motorcycle and to know the influence of track variation to engine temperature. The result of the data obtained from the engine temperature data before and after the installation of oil cooler system is that there is difference of engine temperature before and after the installation of oil cooler system on the Honda Supra X 100 motorcycle with an average of 25% reduction and there is influence of track variation to engine temperature. The effect makes the temperature drop in the front of the head is larger than the orther surfaces.