2011 GAS GAS XC 250 4T, The XC 250 FSE is the latest addition to the range.GAS GAS has installed an engine proven beyond all doubt: the legendary 5-valve Yamaha engine, which marked the rebirth of 4-stroke off-road in the late nineteen-nineties.With optimum power throughout the curve from low to maximum rpm, this Japanese engine perfectly embodies the GAS GAS frame philosophy: always enough but never too much.