2012 s40 want to know cable sizes for 14in ape hanger handlebars?

Mount the new bars on the bike and measure from the control connection on the bar to the carb, going along the same route on the frame that the cable will be going.  Measure to within an inch or less for best fit.
It is easiest to use a wire or chord to follow the route and mark the exact length, then lay it out straight and flat and use that measurement it for a more exact fit.