Sounds like a normal compression kickback. To reduce the possibility of putting your knee into your chin, just ease the kickstart a few times and get a feel for where the compression is. Take it just past where it locks up and then give it a bootfull. What this does is put the piston just past top dead center and if you pick it right should start her everytime.
Converted Electric start XT600 Owner.
Townsville Queensland Australia.