ENGINE COOLING

Several explosions per second generating loads of horsepower may sound cool but it can get very hot. The combustion chamber is built to handle extreme temperatures but the engine needs to run as cool as possible before its tolerances get the better of it. Low-capacity engines that are designed for low- and medium-performance applications, such as singe-cylinder 100- to 150cc commuter motorcycles producing 7.5-15 PS, make do with air cooling. The cylinder has fins outside that facilitate heat dissipation. Higher-performance engines, especially high-revving motors, need more efficient temperature management and use liquid-cooling: a setup that circulates coolant through waterjackets built within the engine and uses a radiator to assist with cooling. Engine temperatures can touch 125° Celsius on average at idle speed for a liquid-cooled four-cylinder engine.