success in racing set the tone for Yamaha, as competition in many varieties of motorcycle racing has been a key endeavor of the company throughout its history, often fueled by a strong rivalry with Honda, Suzuki, Kawasaki and other Japanese manufacturers. Yamaha began competing internationally in 1956 when they entered the Catalina Grand Prix, again with the YA-1, at which they placed sixth. The YA-1 was followed by the YA-2 of 1957, another 125cc two stroke, but with significantly improved frame and suspension. The YD-1 of 1957 was a 250cc two-stroke twin cylinder motorcycle, resembling the YA-2, but with a larger and more powerful motor. A performance version of this bike, the YDS-1 housed the 250cc two-stroke twin in a double downtube cradle frame and offered the first five-speed transmission in a Japanese motorcycle. This period also saw Yamaha offer its first outboard marine engine. Success and growth in the 1960s By 1963 Yamaha's dedication to both the two-stroke engine and racing paid off with their first victory in international competition, at the Belgian GP, where they won the 250cc class. Success in sales was even more impressive, and Yamaha set up the first of its international subsidiaries in this period beginning with Thailand in 1964, and the Netherlands in 1968. 1965 saw the release of a 305cc two-stroke twin, the flagship of the company's lineup. It featured a separate oil supply which directly injected oil into the gasoline prior to combustion (traditionally riders had to pre-mix oil into gasoline together before filling the gas tank on two stroke engines). In 1967 a new larger displacement model was added to the range, the 350cc two stroke twin R-1. In 1968 Yamaha launched their first four-stroke motorcycle, the XS-1. The Yamaha XS-1 was a 650cc four-stroke twin, a larger and more powerful machine that equaled the displacement and performance of the popular British bikes of the era, such as the Triumph Bonneville and BSA Gold Star. Yamaha continued on with both the two-stroke line and four-stroke twins at a time that other Japanese manufacturers were increasingly moving to four cylinder four-stroke machines, a trend led by Honda in 1969 with the legendary CB-750 four-stroke four-cylinder cycle. Two stroke era begins: the 1970s In early 1969, Yamaha added reed-valve induction to its previously piston-ported designs to produce the twin-cylinder RD and single-cylinder RS families, with variants in a number of capacities. There