Here's the Wikipedia explanation Brad.
History
Work started on the construction of the first workshops of the arms factory originally called “South Bohemian Armament Works” (“Jiho?eská zbrojovka”). The company merged with an arms manufacturing plant in Vejprty and with a factory in Prague in 1922. This gave birth to the constitution of a stock company under the name of “Czech Armament Works in Prague of the Manufacturing Plant in Strakonice". They produced pistols, air guns, and automatic guns which all became successful products.
It was not until 1929 when the growth of the Czech Armament Works reached a turning point. With the downturn in weapons sales after World War I, the company acquired a bicycle parts manufacturing plant in Kralupy on the Vltava River. Bicycle exports destined for several countries in Europe, Asia, Africa and South America started to expand. Production of motor-driven bicycles started in 1932. Three years later, the first motorcycles made in Strakonice entered the market. This marked the beginning of an era of great success for the ?Z brand. In a short time, the company became the biggest manufacturer of motorcycles in Czechoslovakia. Consequently, business success resulted in a further extension of production activities by introducing chains and machine tool production. During World War II, the factory came under Nazi occupation and was converted to the wartime manufacturing.
Like most large industrial enterprises, this stock company was nationalized in 1946. Due to the post-war political situation, arms production in the Strakonice plant was then closed down. In 1948, ?Z Motorcycles merged with their main rival, Jawa.
CZ 250 typ 455Motorcycle development and production as well as competition victories in 1950s and 1960s enabled the ?Z brand to be among the world’s most successful makers of competition and street motorcycles. After World War II, ?Z was the second largest motorcycle manufacturer in Europe. It was during this period that the company experienced its greatest racing successes. It began competing in the 250 cc and 350 cc classes of Grand Prix motorcycle road racing. These bikes, although technically refined, were rarely very competitive with bikes from the powerful Italian factories such as MV Agusta, Gilera and Mondial.
In the 1969, the CZ produced a technically advanced model: the 350cc "Type-860" GP, with a V4 engine, developed by the engineer Frantisek Pudil. This advanced bike, with double overhead camshaft, 16 valves, 8-speed gearbox, Ceriani forks and Dell'Orto SSI carburetors, produced 63 horsepower at 16,000 rpm with a maximum speed of 240 km/h. The 350 V-4 achieved several good results: the best being in 1971, at the Czechoslovakian Grand Prix when Bohumil Stasa finished second behind Jarno Saarinen on his 350 cc Yamaha. In 1972, the bike almost won the Austrian Grand Prix. With just few laps to go in the race, the CZ was leading Giacomo Agostini's MV Agusta when it had to retire with mechanical problems. In the 1972, CZ abandoned Grand Prix road racing competitions in order to concentrate its efforts on motocross, a less expensive form of competition.
CZ proved to be much more successful with motocross and became well known for its powerful two-stroke off-road motorcycles. They were the first company to use expansion chambers in their exhaust pipes. During the 1960s, they would become the dominant force in off-road competition, winning seven Grand Prix Motocross World Championships and dominating the International Six Day Trial, a form of off-road motorcycle olympics.
By the 1970s, with the advent of inexpensive Japanese motorcycles, ?Z lost an increasing share of the motorcycle market. Ironically, many of the innovations successfully pioneered by CZ, were copied by the Japanese factories. In 1993, the motorcycle branch of ?Z was bought by the Italian motorcycle manufacturer Cagiva, who intended to use the Czech factories to build their own brand of motorcycles as well as new CZ and Jawa models. The venture failed in 1997 due to Cagiva's financial difficulties and the ?Z motorcycle brand went out of existence. The company changed and started focusing on manufacturing car components - gearboxes and turbofans, besides its traditional production of chains, tools, moulds, castings and machine tools.
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