Cycle News

CN III ARCHIVES BY LARRY LAWRENCE B eginning with Joel Robert's 1964 250cc Moto- cross World Championship aboard a CZ 250, the Czechoslovakian manufacturer went on an im- pressive streak—winning four 250cc World titles (in addition to a trio of 500cc World Championships). That success made CZ the state-of-the-art moto- cross maker of the 1960s. By the 1970s other mak- ers began to catch up and surpass the technology of CZ and the manufacturer never again saw the success in motocross that it had in the '60s, but for a magical period in the breakout decade for moto- cross racing, the name CZ was practically synony- mous with the sport of motocross. CZ began life in 1919 as a firearms manufac- turer in the South Bohemian city of Strakonice. In the 1920s, the company began making bicycles and by the early '30s motorized bikes. Like most large industrial enterprises under the communistic regime, this stock company was nationalized after World War II. Due to the post-war political situation, in 1948 CZ Motorcycles merged with its main rival, Jawa, but the two makers maintained distinction in the models they produced and areas of specialty. By the late 1950s, CZ began competing and doing well in motocross events across Europe using 175cc trials machines ridden by factory CZ trials riders. With further development by riders such as Vlastimil Valek and Karel Pilar, by the mid-1960s CZ became one of the main bikes of choice for privateer motocross riders in Europe. The reason unsponsored riders favored the machine was that it was not only light, fast and nimble handling, but first and foremost it was a very reliable machine. That was big in 1960s mo- tocross racing, where innovative designs helped the sport grow, but were often unproven and resulted in a lot of machines breaking. CZ took a more conservative approach. Its design was considered fairly basic and straightforward. While many makers experimented with countless forms of linkage suspension and finicky two-stroke rotary valve schemes, CZ in- stead went with the tried and true telescopic forks front and swing-arm rear suspensions and a con- ventional two-stroke motor design. Perhaps the only thing that made CZ 250s stand out was the twin (low-pipe) dual exhausts emanating from the single cylinder. The dual exhausts allowed for smaller diameter pipes, allowing the chambers to be tucked away more safely under the machine. The mid-'60s era, CZs were known for low- speed pulling power. Instead of using the more typical path of using a long-stroke engine to reach broad power characteristics, CZ instead got grunt from the decidedly short-stroke (70mm bore and 64mm stroke) and developed maximum horse- power at just 5900 rpm, and was even a work- horse from as low as 2000 rpm. Power (rated at 26 bhp) didn't fade until 7400 rpm, so it had a healthy 5000 rpm power spread. The forgivable powerband was produced by way of generous intake, exhaust and transfer ports with relatively CZ 250: THE 1960S STATE-OF-THE-ART P118

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