To understand better the real benefits of the revolutionary inline-four engine that powers the 2009 R1, the manufacturer has created a video explaining the technology behind it. No, not this one!
The combustion torque is produced when the air-fuel mixture explodes, rotating the crankshaft. But when a piston isn’t pushed by the force of the blast, the crankshaft is still rotating due to inertia of the crankshaft. This generates inertial torque which is bad for linear power out of the corners. It also affects composite torque, which is a combination between the previous two so that is why Yamaha needed the crossplane crankshaft engine.