2si  2si was an American engine manufacturer located in Beaufort, South Carolina. The company was a wholly owned subsidiary of the AMW Cuyuna Engine Company, formerly known as the "Cuyuna Development Company". The company acquired a line of two-stroke engines that were originally designed and produced by "JLO" of Germany and marketed them under the "Cuyuna" brand name for snowmobile and later ultralight aircraft use. Later Cuyuna formed a subsidiary "Two Stroke International", commonly known as "2si", to produce and market the engine line. Cuyuna ended selling engines for aircraft use, but instead switched to only marketed them for industrial, marine, auto racing, kart and all-terrain vehicle applications. The company seem to have gone out of business in 2014.