A pit bike is a small off-road/on-road motorcycle originally used for riding around the   pits or staging area of a motocross race. Since the early 2000s pit bike   racing, a sport similar to motocross, has become popular in the United States,   especially in Southern California. The name pit bike originated from the use of a Honda Z50 to ride around the pit areas of dirt bike   races and race events across the United States. The fairly cheap price and the   mobility of these bikes made them easy to use at racing events. By the time the trend caught, Honda had changed the name from Z50 to XR50 in   1999 and made great changes to the bike. A few of these changes include a   plastic gas tank, single rear shock, spoke wheels, seat, plastics, total   redesign of the frame, and the total appearance of the bike. As teenagers and   young adults began to show interest in Z50’s, companies started to be formed   which make upgraded aftermarket parts for pit bikes that make them comfortable   and powerful for bigger riders. Some of these parts include heavy duty   suspension, tall handle bars, tall seats, and big bore kits. As more and more   people put these upgraded parts on their Z50’s their popularity grew and lead to   pit bike races across the United States.

In 2002 Kawasaki came out with the KLX110. This   bike, as with Honda’s XR50, was designed for smaller riders. The 110 is bigger   and faster than an CRF50 and has a greater top speed so it needs fewer parts to   make it comfortable for bigger riders. Pit bike riders realized this and started   moving their focuses to the KLX110. Due to the popularity of the sport, many pit bike race series have appeared   in various parts of the United States. Some examples of such series are the 2-Up   Minis and Masters of Minis race series,  the   Sho-Me series in Missouri, and the annual Mini Moto Supercross race held the day   before the final round of the AMA Pro Supercross series. Since 2003, starting with the SDG Speed Mini, an alternative to upgraded   kids' bikes became available. In 2003 Xtreme Motor Corp, a company founded by   ex-motocross champ Guy Cooper, and SDG began producing fully upgraded Chinese   pit bikes, unfortunately in 2009 they went out of business. These pit bikes were designed around the Honda CRF-50's frame and   used larger displacement engines, as well as tall handle bars, stronger   suspension, and various other upgrades. The demand for these production minis   was not quite as great as these companies had anticipated. Currently available production pit bikes   include Coolster, SSR, WMX, APOLLO, and ORION. Companies like OGM,   Thumpstar, and Sikk MX no longer have any pit bikes for sale.