The Robin engine has always been built by Fuji Heavy Industries of Japan. Generally a well regarded engine, but in the 1980's and 1990's Fuji was a little late adding innovations such as electronic ignition and overhead valves. Today, Robin is right behind the Honda GX OHV engine and considered superior to the Honda GC and Kawasaki motors.
Fuji originally partnered with Teledyne Wisconsin for distribution and parts support. Fuji felt they didn't have a meaningful footprint in the US and Wisconsin did not have competitive offerings below 10hp. In theory the partnership should have benefited both parties.
However, Wisconsin has foundered and Fuji was dissatisfied with their performance. Also, Fuji had been successful with the Subaru automotive line, increasing name recognition and quality perception. When renewal of the partnership approached, Fuji elected to take over distribution and support, and rebadged the product as Subaru-Robin. At the same time, Robin freshened the line by eliminating flat head engines to meet EPA emissions requirements and introduced several modern OHV and OHC models.
Fuji now markets their small engines worldwide under the Subaru umbrella and there is currently no ongoing relationship with either Teledyne or the newly constituted Wisconsin Engines.