Screamer or Big Bang.. New racing technology now in stock bikes..
Yamaha R1 has a Yamaha M1-like big bang firing order. The first time a big bang engine has been used on a production bike, Yamaha is calling it "Cross plane Technology". It puts each connecting rod 90º from the next, meaning the cylinders fire at 270°- 180°- 90°- 180°. This spreads out the power pulses to the rear tire, allowing it to regain traction in between each pulse. The result is more usable traction under large throttle openings, meaning riders will be able to accelerate out of corner earlier and harder.
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As predicted and debated on the web for a while the new R1 is the first Big Bang stock bike. A technique used by manufacturers with inline four-cylinder engine layout like Yamaha and Kawasaki. Ducati, Honda and Suzuki all have V4 engines. The Big Bang concept has its roots in flat track racing, where Harley Davidson big-bang V-twins dominated for decades. Then more big bang engines was put in Suzuki test bikes in the early 1970s. Even Cagiva tried their Bombardone engine in the mid 1980s, but it was finally Honda that made the big bang design an integral part of road racing 1992 with their NSR500 Mick Doohan won the first four races that season, then crashed so badly in practice at Assen and missed the next four races. Whereas a screamer engine due to its high-pitched engine note - features an equal amount of time between the firing of each cylinder, 'big-bang' engines have an uneven firing order. A standard inline-four Screamer fires its cylinders at regular intervals - one cylinder every 180 degrees of crank rotation. This creates a constant delivery of power to the rear wheel, which can make it difficult to maintain rear-tire traction, and also a lot of engine noise at high rpm. Over 12,000 rpm the motion of the moving parts inside a engine become a big problem for the rider and he have huge problems to hear what the tyres is 'saying' to him. A rider always needs to listen carefully to his tyres, and talk back to them directly with the throttle. A screamer engine makes it really hard to 'hear' as in Moto GP the useable rpm is 14,000 to 17,000 - sometimes up to 19,000. So the connection between throttle and tyre is not good with the screamer option. The "big bang" engine attempts to transfer this characteristic to the inline-four by changing the firing intervals of the cylinders. By firing two cylinders close together (producing what sounds like one 'big bang'), followed by a long break, then the other two cylinders in close succession, then another long break before the cycle begins, a "big bang" motor gives the tire some recovery time. This gives enormous benefits to ride ability and tire wear. A communication process between the rider and rear tyre, made via the engine and becomes increasingly distorted at high rev/min. 'Big-bang' engines keep this distortion to a minimum. Internally the big-bang engine is very smooth during its rotations. It sounds like it is fluctuating a lot, because of the uneven combustion timing, but the reality is that it is very smooth at high rpm. The disadvantage is that these uneven firing intervals throw off the balance of the motor, creating excess vibration that can be damaging to the bike and annoying to the rider. The life span of the motor is also affected, since there are now two large power pulses per power cycle instead of four smaller ones. The power output of modern 1000cc sport bikes have already climb to ridiculous heights, so now ride ability will start to become the deciding factor for many potential buyers and I think Yamaha's chief engineer, Masao Furusawa will stay with big-bang engines even if a traditional screamer produce more "power" on the wheel....