.... hay do you think I should re set those floats in the bike to 22m from 27mm ?
Man, I wish that my albums hadn't been damaged from the forum software upgrade. So much text data lost. Anyway, referencing this entry on float bowl capacity (plus the next two entries):
http://www.xs650.com/media/xs1b-car...mm-level-means-that-each-1mm-dif.23305/#media
Means that your missing 5mm of fuel height translates to a 12.7cc loss of fuel. And, for both carbs, totaling about 25cc of missing fuel. Now, suppose that you've got a healthy XS650, getting 50mpg, and you're traveling at 60mph. You're consuming about 60/50 gallons per hour (1.2 gph). Which is about 4542.5cc per hour, 75.7cc per minute. That missing 25cc represents 1/3 minute (20 seconds) of ride time.
So, what that means is, imagine that you shut off the petcocks while at that 60mph cruise. After 20 seconds you'll be at the fuel level that your 27mm setting gives you. Is it starting to feel like it's leaning out on you? Probably. The original total capacity of the carb bowls usually gives you about a minute of ride time, but you'll feel the leanness well before they go dry...