As a platform for customization and personalization, the Bonnie is hard to beat, with a huge aftermarket cranking out go-fast bits and faux Ace Café clobber for both bike and rider. Poorly done or ill-advised mods are about the only thing you need to beware of when looking at used bikes. Watch out for the usual suspects—oil leaks, dirty or kinked drive chains, hard starting, oil smoke from the mufflers. Many bikes go well past the recommended valve-clearance intervals with no issues, but ask if they’ve been checked. Oil consumption isn’t the modern Bonnie’s weakness, unlike its ancestors, so a used one that smokes or needs constant topping off is suspect.