When i put my kx 85 in first(1 down) it feels like its in second. it boggs down when i try to take off.?

It feels like it's in second compared to what? To the way it used to feel, to the way the bike you had before felt? Most all 2 stroke race bikes do bog unless you come out of the hole fairly aggressively which is why I never recommend one to a non-racer.