The FZS runs a very slack chain as standard, avoid bikes that have been run with a tight chain this will knacker the output shaft bearing and in turn will allow enough movement in the gearbox to knacker the selector forks. So unless you are after a project and are fairly spanner competent or know some one who is, then avoid a Fazer than jumps out of second gear.
Other than that, seized and corroded rear calipers, speedos not working, rotten down pipes, and making sure the front sprocket is held on with the revised nut. Cracked inlet rubbers are usually nothing to worry about.
