A flat-four engine has 4 cylinders organized in an reverse direction alongside a common crankshaft. The pistons go away from one another at the same time. Examples are Honda CB750 and BMW K1200RS. The fork is basically a two-legged part with the frame that retains the front wheel in place. https://bikeengineguard38087.atualblog.com/41399592/predator-ghost-212-racing-engine-options