2013 Kawasaki KX250F Specifications The Kawasaki KX250F has a boosted compression ratio of 13.8:1 (vs. 13.5:1). This was accomplished by shortening the cylinder minutely (36.2mm vs. 36.3mm). The ignition rotor is heavier to help make the power delivery more tractable. A new exhaust system graces the right side of the bike with a Mega Bomb-type header which Kawasaki calls it an Acoustic Resonator chamber. Hariyono86.net