Flywheel shaft / nut

[kcxx95]

Help please, partially stripped flywheel shaft - need to know the flywheel nut and shaft thread size / pitch, to purchase die for cleaning the shaft threads. The nut is a 12mm - need to know the thread pitch. It is not a 1.5 or 1.25 that I know of, so must be lower pitch, possibly 1 or .75??

Thanks kcxx95