with the 400 you should be able to pop it up farily easy. Hold the brake in and then give it some gas...let the rpms climb enough so that they are sorta high but do not make the back tires to spin...let go of the break slam the throtall pull back and then find the bp...

 

on a 400 it should be easy as hell...just sit as far back on the seat as you can, and hit the gas...pull up a little bit on the handle bars, and you should be up!