Engineering is easy. Lean on decades of technological progress, R&D like hell, and a modern manufacturer can build a mechanically competent motorcycle that satisfies the masses.
Style, on the other hand, proves elusive. It slips and shifts, deflecting fleeting trends and prevailing tastes while flirting with the culture zeitgeist. On a rare occasion a bike?s looks will resonate grandly, alchemizing desire through seemingly incidental gestures like the arc of a fuel tank, the chamfered edge of a cylinder head, or a just-so wheel-to-engine-to-handlebar proportion. But when it?s not quite right, motorcycle styling can fall off a cliff like a fashion faux pas from yesteryear.

Harley-Davidson?s Sportster has profited richly from 64 years of evocative design, a freakishly enduring stretch that has outlasted some manufacturers. The Sporty?s stripped-down allure captured the imagination of 26 year-old Leo Payne, who purchased a first model year Sportster in 1957 that he eventually tinkered with and raced his entire life. So bullish was he on the Harley that he delighted in riding his American outlier with the edgier BSA and Triumph crowd in his hometown of Cedar Rapids, Iowa, because the local HOG group was too geriatric. Payne bored-out, shaved down, and optimized his Hog over the course of decades, transforming it into a nitromethane-burning animal dubbed the Turnip Eater, so named for its appetite for hopped-up Triumphs.

In its ultimate iteration, the transmogrified Sp...