Same situation for me...first bike, first carbs; I can handle the minor stuff but the carbs definitely psyche me out.

 

hey, i'm fairly certain that tube comes from the evap canister check out your service manual on page 3-16 theres a diagram that shows it coming from there

if you don't have a manual you can get it online here
http://tbbracingdotcom.files.wordpre.../cbr600-f4.pdf

myn is doing the same thing let me know if you find a solution