I don't know about the FZ6 specifically, but Yamaha bikes have a good rep for running a good long time. 24 K doesn't sound too high, but it does sound like it was the primary transportation for the previous owner. Or, he made a lot of road trips. If it was road trips rather than a bunch of city driving, the bike should be great ... less wear on the transmission, brakes, etc. Highway miles are good miles. Even at that, 24K of city miles isn't too high. I'd base my decision on the condition of the bike. If it looks like it was well taken care of, it probably was; especially if he has maintenance records. Trust your instincts, and happy hunting!