Thee two motors were built by Fuji for Polaris starting in the late 1960’s. The 4 cylinder inline motor was built as an answer to the Arctic Cat King Kat 4 cylinder. After a great deal of testing and a lot of broken crankshafts, Polaris abandon the idea after one of the top Fuji Engineers explained “Four cylinder inline – NG!” meaning “NO GOOD!”.
The V4 motor also had unsolvable reliability issues with the crank.
Jerry Schenk, the mastermind behind all the early Polaris race motors, cleaned them up and put them on display at the Polaris 45th where this photo was taken (photographer unknown).
Yes, they still exist, but Polaris keeps a tight grip on them.