599cc was Yamaha's calculated rebellion against the notion that a road engine must trade revs for manners. The R6 could spin past 16,000 rpm because its 67 mm bore and 42.5 mm stroke cut mean piston speed, while a short-stroke cranktrain reduced inertia. Small pistons helped. The wide bore gave the valves room to breathe.The real trick was valvetrain control. Double overhead camshafts, four valves...More