The top speed of a 49cc pocket bike can vary depending on factors such as the specific model, weight of the rider, and terrain conditions. However, on average, a 49cc pocket bike can reach speeds between 25 to 35 miles per hour (40 to 56 kilometers per hour). It's worth noting that some pocket bikes may have speed limiters or governing mechanisms to restrict their top speeds for safety reasons. Always ensure you are familiar with the manufacturer's guidelines and local regulations when operating any motorized vehicle.