More so than cars, motorcycles have great variety in engine layout options. Many times it’s driven by type of bike, number of cylinders, and how much the engineer had to drink the night prior to first getting out his slide rule. Also unlike autos, a motorcycle’s engine becomes an integral and visceral part of the look and emotive energy that the bike gives off. Some bikes rock a very traditional format, regardless of size, as driven by some ancient code imprinted in their DNA. A Harley that isn’t a V-Twin seems an abomination, despite models that carried other layouts in decades past. The long-L of the Ducati desmo twin is equally emblematic of the brand, as is the chromed and canted four in a row that powered hundreds of thousands of Hondas from the seventies on. BMW boxer twins, Triumph Bonnie verticals, Moto Guzzi’s tractor-based V-twin, mounted at a right angle from where it would be in a Harley. The raw mechanical beauty of the Vincent HRD 500-cc single, or maybe the insanity that was the Honda CB500-based Benelli 750 Sei, there’s a motor and a cycle to set just about anyone’s heart a flutter whenever one passes by. Do any of them make your boat float? I can tell you, for me it’s the traditional English Twin that really kicks my starter, although hearing the desmo valvetrain and dry clutch on a Duck is also molto bello. So which two-wheeler turner tickles your fancy? Image sources: [The Kneeslider, The Biker Zone]