Just checked out the
www.gearingcommander.com site. With stock gearing and stock tires on a 2008+ ninjette, at 9000 RPM in 6th gear the expected road speed is 73.1 mph. Our tachs have a fudge factor, and our speedos certainly have a fudge factor, so I wouldn't be immediately alarmed. It may be reading a little higher (or a little lower) than other bikes, but it doesn't mean there is anything particularly wrong with the bike. There very well may be.
, but this data point alone isn't enough to come to that conclusion.