The Fascinating Story of the Ariel Square Four, the Engine So Complex It Overheated Itself to Death

The Ariel Square Four was one of the most ambitious motorcycle engines ever built—a compact four-cylinder masterpiece that promised smooth power, luxury touring performance, and engineering brilliance. But its clever square layout came with a fatal flaw: heat. Packed too tightly for its own good, the rear cylinders struggled to stay cool, turning innovation into a mechanical nightmare. This is the story of a legendary British bike whose genius design ultimately helped seal its fate.