It depends if your raise them up and back (i.e. with straight risers), or raise them on a vertical plane (i.e with risers that can pivot forward, so the handlebars remain vertically inline with the current handlebar clamp position).
I originally tried the simple straight 30mm spacers (that move the bar up and back), and had slack to go higher but could not find any taller risers. Problem was I am 6'4", 36-37" arms, and with the 30mm spacers I did have a little more rise but still not enough (in addition moving the bars back was detrimental to seated comfort).
I wound up with a pivoting 2" riser, pivoted forward to maintain the stock handlebar location, combined with bars 1 1/2" higher than stock iirc (so about 3 1/4" higher total), and finally the little WR fits nicely while stand up riding (albeit with 3/4" lower footpegs). Using all stock cables (most at the length limit, throttle cables moved to the bottom of the handlebar instead of the top).
An unanticipated bonus was with the stock seat/bars/location, my butt would HURT after about 30-40 miles, so I was looking for an aftermarket solution to that. With the raised bars, somehow I sit differently and I can ride through a tank of gas and then some on the stock seat (yesterdays ride was 100+ miles through the beautifully blooming southern California deserts near Pioneertown), butt is fine.