At the Intermot show in Cologne, Yamaha introduced a three-cylinder concept engine that the company believes "will open up new horizons in riding enjoyment." The new engine is based on the crossplane concept used in the YZF-R1 and the company's M1 MotoGP bike. While very little other information was released, the press information states that the new engine is destined to play an important part in Yamaha's future.
The crossplane crankshaft in the R1 uses four evenly spaced throws, with 90-degree spacing between each cylinder as opposed to 180 degrees in a more traditional layout. According to Yamaha, this reduces "inertia torque," resulting in better feedback to the rider. Because the 90-degree spacing introduces a primary rocking couple vibration, however, a counter-rotating balancer shaft must be used. In the R1, this balance shaft sits in front of the motor; in the M1 MotoGP bike, the shaft sits between the crankshaft and transmission and is also used to reverse the rotation of the crankshaft.
Transitioning the crossplane crankshaft concept to a three-cylinder engine would infer three evenly spaced throws of 120 degrees each, with a balance shaft to offset the resultant rocking couple vibration. Interestingly, this is the layout used in the Triumph and MV Agusta triples. The MV even uses its balance shaft to reverse crankshaft rotation, just as the Yamaha M1 does. Yamaha has released very few details other than its display at the show and some external engine images, so we will have to wait to see exactly what - if anything - differentiates Yamaha's crossplane concept three-cylinder engine from what will be its Triumph and MV Agusta rivals.