How fast can a 4 stroke 40 cc dirt bike go?

A 4-stroke 40cc dirt bike typically has a top speed ranging from 30 to 40 mph (48 to 64 km/h), depending on factors such as the bike's weight, terrain, and rider skill. These bikes are designed for recreational use and are often suitable for younger or novice riders. Performance can vary based on the specific model and any modifications made.