The K.O. engines are encountered relatively infrequently outside of Japan because they were never marketed internationally with any great fervor. The well-made K.O. diesels are the best-known model engines produced by the company, which is far better known today for its R/C products marketed under the KO-PROPO trade-name, particularly in relation to model R/C car racing.  In an article to be found elsewhere on this website, we share a really close-up look at the K.O. diesels of the 1950’s and 1960’s, including bench tests of several representative examples.