strechedf4600

Ok so ive searched but didnt find any answers specific to my need.This is my first post. i have a 99 cbr f4 streched 6 inches that i bought streched. I am attempting to wheelie the bike clutching it up in first.more times then not the bike just does a rolling burnout. so ive seen alot of streched bikes wheelie. but no 600 extended doing wheelies. is it me?the tire is hot and pressure is lowered to about 20.plenty of power seems possible.any tips or opinions?