What is different is the ECU mapping. The YZ250FX now features the same adjustability as the YZ250F with its smartphone-based Power Tuner app. In stock form, it offers two different base maps with a two-position map switch mounted on the handlebar. With the light off, which is map 1, the engine is more responsive and quicker revving. With the light on, map 2, the engine has a smoother response and is slightly slower revving. With the Power Tuner app, you can make adjustments to both base maps on a 4x4 grid. Fuel adjustments are made with steps of -7 to +7 with a range of one step, which equals a 2-percent fuel change. Ignition adjustments are from -9 to +4 with a range of one step, which equals a one-degree change.