jerks

Hi ,i have a 2005 Kawasaki z750 The problem is ,when i ride the bike and i go past 8500rpm the bike strarts to jerk ,as if there is not enough fuel .The rpm range from 8500 to 9000 at that moment and do not go above 9k ,The problem is happening from 2-6 gear (i didnt test gear 1) and there...