KZ650C1 fork cylinders do not have a hex depression, only a round hole as in the picture. To hold this while disassembling the forks you can make a tool by super gluing a 9/16 inch OUTSIDE diameter vacuum cap to a 3/8 inch steel rod and putting other end of the rod through a big bolt to make a t-handle to give you a way to hold the rod. I put a clear tube on the rod before gluing on the cap to protect the fork top threads. The friction of the rubber vacuum cap will hold the fork cylinder, but you must apply much force while someone else uses an impact wrench to loosen the fork cylinder bolt. This tool makes tightening the bolt to the correct torque spec easy.
I should mention that I've never needed a holder because I remove the damper rod bolt with an air wrench BEFORE removing the fork cap. This way the preload on the spring holds the damper rod in place. Might not always work, but it has for me.
a sharpened broom handle worked for me too. funny enough that i unscrewed the right bolt without the broom and failed with the left one. but when i unscrewed the left bolt with the handle, the handle came out with the cyl, but it took quite awhile to remove the right cyl the same way
ps ahh well my cyls have 12 edge hex depression or whatever
Nelson, I have used the same method with much success up until the last year. My sons 650 had them stuck, a kz1000 had one stuck and then I was working on my Z1 and had enough to make a tool for removal. The reversible end has a 17mm hex to fit the ones that have a 12 point socket end, and the other end fits the Z1 rods. The other rods with just a hole in the end I use a #6 screw extractor.
Over 30 years with z1's, Currently down to only one 75, a j model dragbike, and 2 KZ1000 dragbikes.