Some updates, just so other people with KZ550's and TK carbs can get as much as possible
I recently got my hands on an O2 wideband tuning kit (spendy, but awesome) and another carb tuning tool that lets you see into the combustion chamber and tell what's going on (lean or rich) called a Colortune by Gunson.
I had drilled out the pilots to #78 which ends up being .39mm the mixture screws were all almost bottomed out attempting to richen the circuit as much as I could. I was able to get cyl 2/3 to do "OK" and not run lean, but they are 1/4 turn or less from bottom. So I'll be drilling the pilots out ONE more size to the # 77 drill bit, giving me a Pilot size of .44mm I would hope to have some adjust-ability using the mixture screws as now I should be TOO rich with the screws all the way in. This should put me to the almost factory specs of 1 1/4 turn I would hope (crossing fingers)
After the pilot circuit is "fixed" I'll move forward with the O2 sensor and see what's going on with the rest of the rev range. Just thought I would get as much information out there as possible.