Join Date: Dec 2004
Location: Altofts zx-12r B4 UK
This may sound odd but have you got play in the rear wheel cush drive rubbers, as slack in here would be transferred back into the gearbox.
The slack is easy to fix if you have an old push bike inner tube? just cut 4 pieces 1.5cm by 1cm squares and stick them to the back stops of the wheel and then replace the cush drive rubbers and the wheel will have no slack in it.
For Tech Questions Bike Model letters and Country are more useful than saying the year, for UK owners anyway, as registration year is not always the year of manufacturer model.