I have -96 600cc Cbr. It is restricted to 25kw by limiting the fuel suction in carburetor I believe, and I have the original parts.
But I don't know the name of the part and I cant identify it in this picture.

http://img230.imageshack.us/my.php?image=carb26of.jpg

How difficult would it be to change?

I can upload picture of the orig parts later. It is just a black short tube.

 

hi, mines restricted 2 but mine is restricted apprently in the inlet rubbers by a washer, im currently un restricting it now i will tell you tomo how it goes.

james