The material used in a bike engine can vary depending on the specific type of engine and the manufacturer. However, the most common material used for the engine block, cylinder head, and other major engine components is aluminum alloy. Aluminum alloys are chosen for their lightweight nature, good thermal conductivity, and corrosion resistance. These properties help in improving engine performance and efficiency. Other materials such as steel, cast iron, and titanium may also be used for certain engine components, depending on the specific requirements and design considerations of the bike manufacturer.