The all new YAMAHA Fuel Injection(FI) Blue Core engine of YAMAHA FZS FI uses advanced sensors and actuators to calculate and deliver the optimum amount of fuel to the engine – enhancing both performance and mileage. New 149cc engine with a compact hemispherical combustion chamber designed to deliver better fuel economy and acceleration performance has been developed. It achieves a 14% improvement* in fuel economy. The bore x stroke dimensions are 57.3 mm×57.9 mm, making it a relatively small bore engine, and its intake/exhaust valve layout is designed to best match the hemispherical combustion chamber. In combination with the optimized intake and exhaust port shapes, this design increases combustion speed and helps achieve excellent combustion efficiency. The new engine further improves fuel efficiency and the feeling of acceleration while retaining the excellent performance qualities of the current FZ engine.