A big surprise arrived in 1990 was the advent of the ‘Big Bang’ engine. In this configuration the firing of each cylinder was offset 90°, meaning that instead of each cylinder firing at 90° intervals, each set of two cylinders fired 180° apart. The slight reduction in maximum power that resulted was more than offset by the improved torque characteristics caused by the increased amplitude in combustion torque waves. Traction during acceleration was markedly improved.
This was a major turning point in engine development, and the NSR’s engineers experimented with various firing orders and crank angle/ignition timing settings. As the bikes became easier to ride, lap times began to drop. Usable power became more important than maximum power. Chassis upgrades included such trick parts as expansion chambers and other parts made of titanium, helping to reduce machine weight by more than 15kg.
Around this time another gifted rider appeared on the scene. Mick Doohan had been battling with Yamaha’s Wayne Rainey and Suzuki’s Kevin Schwantz, finishing 3rd in the championship in 1990 and 2nd in 1991. His time had now come.
By the time 1992 rolled around, a new 68° irregular firing order was being used. Each pair of cylinders fired simultaneously at 68° and 292° intervals. The resulting irregular combustion torque wave shapes delivered markedly superior traction. And just by chance, thanks to the crank phasing, the 112° V angle cancelled out the theoretical primary vibration, eliminating the need for a balancer shaft. For the first time since 1986 this allowed a return to a triple-shaft engine, and a more rigid and precise engine structure. This new engine had a unique exhaust note, leading observers to call it a ‘screamer’ engine. In the bike’s first outing, the rain-sodden Japan GP, Mick Doohan rode the ‘screamer’ to victory. This win was especially impressive because prior to the screamer engine the NSR500 was difficult to ride in the wet.