New here

new here to the harley world and have a question. i have a 94 sportster that i got last year and have noticed that when accelerating at WOT the bike is kinda sluggish to begin with and then out of no where at a certain RPM or throttle position (not sure which) it accelerates and runs like a scolded dog. almost like it hits a powerban. its like night and day. is this normal or is the acceleration supposed to be more consistant and gradual and power start more at the lower end? to my knowledge bike is stock and has stock cv carb. drag pipes and different air filter is all.