The first Sportster appeared in 1957 under the XL-57 factory designation (and 54 ci). For 2006 the bikes are now served up in several flavors, including the 883-XL 883, 883 Low-XL883L; 883 Custom-XL883C; 883R-XL 883R; 1200 Custom-XL 1200C; 1200 Roadster-XL 1200R; and 1200 Low-XL 1200L. The designations are fairly straightforward and allude to engine displacement (883 and 1200cc), performance enhancements, and bodywork/seat height. But the venerable XL designation is carried forward. So what did XL originally stand for? "X" usually meant "experimental" or "unknown." "L" could have referred to valve design or just "large," except the Sportster didn't have the L-head design, and as far as "large" goes, it's always been at the other end of Big Twin. Maybe "X" was just the next available letter of the alphabet, or maybe it just sounded more mysterious-a good choice for a new bike. Or maybe it's none of the above.
We'll let Mike Smith and Willie G. Davidson have the last word. Said Mike, speaking of some of the factory designations and names, "I don't know where they come from. Willie G. might know, but every time I ask him he just looks back at me, shrugs his shoulders, and smiles, saying, 'There's sooo much still to learn.' And he's right."