Smoky Mountain Harley-Davidson's Custom Kings entry, Modern Mule, drew on the Sportster's origin story. Here's what they had to say about their bike:
“The traditional story goes that Harley-Davidson really needed a strong entry into the middle weight class to go head to head with the British imports and the Flathead K models that H-D had introduced in 1952 weren't cutting the mustard against the faster and sportier Triumph and BSA twins. Enter the 1957 XL Sportster with 55-cubic-inches of overhead valve power and all was right with the world! Hardly; the original Sportster wasn't exactly what you would call sporty. It was an awful lot like a mini FL; it had full fenders, a large fuel tank, the freight train sized headlamp and fork shroud like it's larger sibling and a heavy two-into-one exhaust system that exited out past the rear tire. To top it off it was saddled with with a very conservative 7.5:1 compression ratio and small valves that wouldn't allow the motor to breath properly. Magazines and buyers both criticized the bikes for being too slow.
Harley responded lightning quick the very next model year with the 1958 XLCH Sportster. Now this was an American two-wheeled hot rod! It had new special cylinder heads with enlarged intake ports, larger valves, racing-style tappets and high-domed pistons that gave it a 9:1 compression ratio. It had cutdown fenders and ran a 19" front wheel and 18" rear wheel combination with Goodyear Grasshopper dual purpose tires. This was time before the motorcycle industry became so specialized and the XLCH was expected to do it all. From a 1958 Motor Company advertisement: 'Get Out Front.'"