1912 Indian Single 500Cc 1 Cyl IOE 2710
Indian’s first, 38.61ci (633cc) v-twin appeared in 1907 with an engine clearly derived from that of the single, though mechanical inlet valves – introduced for 1908 – were an early improvement.
The twin’s rear cylinder continued to form part of the frame until 1909 when a loop frame of the type favored by rivals Harley-Davidson was adopted.
The Springfield Company’s first ‘Big Twin’ debuted that same year displacing 61 ci (988cc).
For 1912 two smaller v-twins were cataloged, the 3 ½ HP 498 cc Model A and the 5 HP 684 cc Model B.
That is to say, the Model A was offered only in the British Indian catalog, it is not listed in the standard “worldwide” Indian catalog for 1915.
Moreover, the standard catalog specifies three types of 5 HP Little Twin, B-1 Single-Speed, B-2 Two-Speed, and B-3 Three-Speed.