It can be argued that country of Japan and their support of Kyotei pari-mutuel outboard boat racing literally saved stock outboard racing. In the mid 1970's new stock outboard motors were few and far between, with the bulk of the engines in use having been built in the mid-50's, it was difficult to generate new interest in the sport.
Enter the Yamato Corporation of Japan, and their exportation of the Yamato 80 engine into the United States. Almost overnight, racers and would be racers could buy a virtually new engine for $400-$500. The engines were run for about one year on the Japanese Kyotei circuit, sent back to the factory and sold refurbished as surplus around the world. The result was tthe introduction of the OSY.400 class (C Stock Hydro in the USA) of outboard racing, now the worlds largest motorboat racing category.
The Yamato 102 was introduced in the mid 1980's and the current Yamato version, the model 302, arrived about 10 years later. Today, Yamato 80's, 102's, 302's and even the occasional 202 can be found actively racing throughout the world in some of the most competitive classes.
Listed below are photos of the varous engines which illustrate the progressive evolution of these engines through the years: