I didn't have much luck with the "broom handle" method. That's why I asked a buddy of mine to weld a tool for me. I used a 1/2 inch nut (19 mm) welded to a metal rod with a "T" handle. It worked great, but I still needed an impact wrench to get the 8mm hex bolt out.
Note: The 1/2 inch nut (or bolt head) measures about 19mm from edge to edge. This works for the 1980's kz750-4's and also I think that periods kz650's. I think the kz1000's used a bigger fork and need a 22 mm head.