The YZF-R15 is the first India-made motorcycle in this class to mount a liquid cooling system for higher engine performance. When the engine is running the combustion in the cylinders heats up the engine. But if the engine gets too hot it loses power. If the engine remains hot for a long time, that causes slight distortion in the engine parts that in turn reduces the gaps between the moving parts. That is why an effective cooling system is necessary to cool down the engine parts and the lubricating oil. There are two kinds of cooling systems: air cooling, which uses the running air flow to cool the engine, and liquid cooling that circulates coolant fluid through passages around the engine. Most automobiles have a liquid cooling system. But, because of the additional parts required, it can make the engine heavier. But, because the system adds some weight to the machine, liquid cooling has not been use on 100 to 225cc class motorcycles in the past.