Originally a pit bike was a bicycle to get racers and mechanics from here to there in the pits. You know, the place where they fix and prep the cars and bikes, as in: “pit stop”.
In the 1950’s people started using the classic “mini-bike” to navigate the pits. These very basically designed bikes (no suspension, improvised breaks) often had a 3 or 5 hp Briggs & Stratton engine which provided a relative high speed.
The 4-stroke, horizontal engine which is considered as the basis for a great deal of pit bike engines today, became popular thanks to the introduction of the Honda Super Cub 50. Millions and millions were produced. According to Wikipedia was this the most successful motorcycle model in history.
Mechanics and racers liked to use these bikes to get around in racing pits. But since its introduction in 1968 the famous “monkey bike”, the Honda Z50 mini trail, started to show up in the off road pits, where we know it all started. The honda Z50 mini trail was the first small Honda motorcycle produced to go off-road. And the perfect thing was that these bikes were small enough to fit in the corner of just about any trailer. Because of the regular updates of the model, like the adding of rear shocks in 1970, you can be sure people started to find out how much fun it was to mess around with these kind of bikes.
From the Z-50 pretty fast came the XR 50R, the CRF 50 and now a street (mini motard) legal version called the XR50, again. This bike quickly became the first bike they ever rode for a lot of big names.
These bikes started to be mass copied by Chinese manufacturers. Most bikers agree that the more expensive Japanese originals of these pit bikes are much better constructed, and will last longer. But you have to consider that the engine used by Honda is Jialing, which is produced in China. Also other Chinese engines like the Lifan or the YX proved to be very well suited for professional use.