The first European race that American rider Kenny Roberts entered was the Imola 200 Miles, held in Italy in April 1974.
During 2005, when Yamaha Motor Co., Ltd. celebrated the 50th anniversary of its corporate founding, Yamaha's factory team in the pinnacle MotoGP class raced YZR-M1 machines with two types of special commemorative colors. One was the American GP version with black "speed block" graphics on a yellow background, while the other was the Valencia GP version featuring the same graphic but with red blocks on a white background.
In contrast to the familiar speed block graphics on the current YZ series of motocrossers and production sport models, these designs were linear with a "retro" look, and in that sense they were close to the original form known as the "chain block" design.
The chain block design was born in the early 70's in the United States. Yamaha had established its original foothold in the US market through motorcycle race successes at the 1958 Catalina GP and the 1961 Daytona GP. Its US motorcycle business partner was Yamaha International Corporation (YIC), a consolidated subsidiary of Nippon Gakki Co., Ltd. (now Yamaha Corporation).
However, as somewhat obscure brand with a short track record, it was not easy for Yamaha to compete in the market against the local US and European motorcycle brands. So, YIC began an aggressive campaign of racing activities to highlight the excellence of Yamaha products. On its race machines, YIC started using a yellow and black color scheme that stood out because of its striking contrast, and a graphic pattern formed by square blocks in a line resembling a chain.
The efforts of riders like Kenny Roberts, winner of back-to-back AMA Grand National Champion titles in 1973 and 1974, Pierre Karsmakers, first winner of the AMA Supercross competition that became a series in 1974, and Karsmakers' successor "Hurricane" Bob Hannah entrenched the image that yellow and black chain blocks equalled Yamaha.
As for factory teams from Yamaha's head office in Japan, the YD racer entered in the Catalina GP and the YDS-1 of the 3rd Asama Highlands Race in the 1950's were 100% red, in everything from the fuel tank to the seat. The 1961 World GP machines ― the RD48 (250cc) and the RA41 (125cc) ― featured a very simple color scheme with a black tank and white cowling. From 1964, however, Yamaha adopted a single red line on a white background.
With Yamaha's return to GP racing in 1973 and the start of the new challenge in the 500cc class, a new color scheme was adopted featuring a navy blue outline was added to Yamaha's trademark red stripe on a white background. In 1978, vertical slits were inserted into the familiar red line, and this was amalgamated with the chain block, which had become a Yamaha fixture in the US racing. This color scheme later became known as the "block pattern," and it was used for all categories of Yamaha machines, from road racing to motorcross and trials. Eventually, it was also used on production sport models as well, and became extremely familiar with the mass media and fans to the extent that it spawned the saying in Japan: "red and white blocks = strobe, yellow and black blocks = Inter-color" (referring to the coloring and graphics of the Yamaha International race machines)
The design arrangement also gradually became bolder and gave rise to a range of variations in block shape, size, arrangement and even coloration. By this time the designs were no longer the "block pattern" of old but a new "speed block" pattern consisting of a chain of rectangular blocks that in itself became a new form of visual identity (VI) that signified Yamaha racing teams.
From the 1980's, sponsor colors were also splashed brightly across the factory machines in memorable designs, but ones that were not unique to Yamaha. It is the "speed block" design that symbolizes Yamaha motorsports and will remain along with Yamaha's tuning fork corporate emblem.