2si / Two Stroke International

2si is an American engine manufacturer located in Beaufort, South Carolina, USA. The company is 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 no longer sells engines for aircraft use, but instead markets them for industrial, marine, auto racing, kart and all-terrain vehicle applications.