BMW’S G-series motor is a reverse cylinder design, which means its exhaust exits from the rear of the engine instead of the front and the cylinder is tilted backwards. But why have BMW done this? On a conventional motor the cylinder leans slightly forward but by tilting it backwards on the G310s BMW have created extra space under the cylinder, allowing them to use an inline gearbox and still have a short engine. Sportsbikes achieve the same goal by using a vertically stacked gearbox, but this solution raises the weight of the gearbox within the bike’s chassis. By tilting the cylinder, BMW have kept the weight low in the frame and kept the engine short and a short engine takes up less space in a chassis, so you can fit a longer swingarm for better drive. BMW aren’t the first to rotate the cylinder head through 180 degrees – Yamaha and Cannondale have done it too but BMW have done it for more reasons than engine length. By making the exhaust exit at the rear of the engine, it is a very short distance to the catalytic converter, that means the exhaust gases heat the cat faster and it gets rid of emissions with greater efficiency. As a result BMW can use less expensive catalytic material, keeping the costs of a bike down – an essential factor on a pricesensitive model.