Are you already using the petcock to turn the fuel on or off? I don't remember the positions, hell I don't remember them for my bike, but if its carbed it should have a reserve. I wanna say down is reserve.
Michigan posted this in another thread, it is for an 87 though, just a starting point.
3 o'clock is Off
12 o'clock is ON (turn counterclockwise from Off or up)
6 o'clock is Reserve (turn clockwise from Off or down)
Found this for a 93 900rr:
Down = On (6 o'clock)
Up = Reserve (12 o'clock)
Forward = Off (3 o'clock)
All I can say is either they are different, or somebody is wrong about the on/reserve. I will say though, I'd let Michigan work on my bike.
Sources:
http://cbrforum.com/forum/showthread.php?t=41757http://www.fireblades.org/forums/honda-fireblade/44203-900rr-fuel-petcock-position.html