Throttle Body Injector(TBI) is a type of fuel injection system that has one or two fuel injectors mounted in a throttle body,and throttle body that can control the engine output. The injectors deliver fuel into the air above the throttle plates.The throttle plates are located in the lower section of the body, from there, the air-fuel mixture enters the intake manifold, where it is distributed to the engine’s individual cylinders. The throttle body injection assembly typically consists of the following: throttle body housing, fuel injectors, fuel pressure regulator, throttle positioner, throttle position sensor, and throttle plates. By adjusting the throttle body via the right hand grip. Turn more on the grip, the throttle body opens more (either via a cable or by electronic stepper motor), you get more air, thus more fuel is supplied, thus more power for your motorcycles .