On most Harley-Davidson motorcycles, the throttle is typically located on the right handlebar grip. It is operated by twisting the grip towards the rider to increase the throttle and accelerate the motorcycle. The throttle control is connected to the carburetor or fuel injection system, allowing the rider to control the engine's speed and power output. It's important to note that the specific location and design of the throttle can vary slightly among different Harley-Davidson models, but the general principle of operation remains the same.