'C' model variation Harley-Davidsons were produced from 1909 until 1918 as Model 5 through 18. Except I have seen no records of a 1912 or 1913 C. They were equipped with a single cylinder 30.2 c.i. engine and varied from the regular models by having 26" wheels and a magneto.
During the same production years there were also A,B,D and E variations. Their features are as follows:
|A||1909-1914||5,6,7,8,9,10||Single||30.2 ci||battery ignition||28"|
|C||1909-1918||5,6,7,10,11,16,17,18||Single||30.2 ci||battery ignition||26"|
|E||1912 & 18||X8E, 18E||Twin||60.34 ci||magneto|
The Harley Davidson Motor Company by David Wright.
Standard Catalog of American Motorcycles 1898-1981 by Jerry Hatfield