A difficult year for the Yamaha team in 2007 resulted in part from a lack of performance, reliability, acceleration and top speed from the M1. Other problems included hard-to-manage fuel consumption, difficulty matching tires to the chassis, and compromises in balancing front/rear grip and braking/turning performance. These issues were addressed with significant chassis alterations, including changes in rigidity, geometry, wheelbase, center-of-gravity height and weight distribution (and, in part, by the switch to Bridgestone tires). The engine was made more powerful through the introduction of pneumatic valves (which reduced weight by 40 percent in the valvetrain) and reducing internal friction. Horsepower increased by 12 percent, while fuel consumption improved by six percent.