I use a Carb Stix on all my triples, and other twins as well for balance adjustment. Expect to see the mercury levels down at the bottom of the vials, maybe as low as two lines from the bottom, this is normal for these engines.
There should be bosses on the other two carbs that are the same place as on the one with the vacuum tube. Drill and tap for vacuum fittings there. Any and all vacuum fittings should be placed between the piston and the rear of the carb slide.
I've really had no troubles with the Uni-Syn
operation. I've done a load of bikes with one, but, Uni-Syn used to have one
that was remote, used a hose from the vial to the adapter.
When using a Uni-Syn, the whole idea is to set the carbs the same, from one to the rest. If the float height is changed from one carb to another in an effort to get them equal, the test is negated.
This carb synching thing is not really fun. Start with the idle. Set the Uni-Syn to one carb, then move it, set the idle stop screw to match the first carb, then do the last one. If the idle is too high or low, reset the Uni-syn and go around again, until the idle speed is where it should be, and all the carbs float the float the same. Sometimes, it takes a little time and effort, and isn't easy.
The last synch is done with the throttle cable at the handlebar holding the carbs open at about 2,500 rpms, bike either on center stand or held as upright as possible, front wheel straight ahead. Set the Uni-Syn to read one carb, then set the others via the cable adjusters, and it may take a few adjustments on both the Uni-Syn and the other carbs to get it done, hang in there, and don't give up.
A large fan on each side of the front end helps keep the engine cooler while doing the carb synch.
Only benefit with a manometer over a Uni-Syn is, you don't have to move the Uni-Syn from carb mouth to carb mouth.
With other methods, as the one described with the drill bits, is, those adjustments rely on the idle synch being dead on. Also, with carb bores not being dead exact, setting the slides by holding the carb slides all the way open and putting as finger into the bores, won't get the carb slides synched correctly for off idle, BUT, will help get them close enough to lessen the time and work needed for synching with the Uni-Syn.
Don't forget to set/check the oil pump setting after you get the carb synch dialed in, and don't forget to lock the cable adjuster down at the throttle grip after setting the off idle cable synch. Leave enough slack so the turning of the handlebars doesn't affect the throttle cable and raise engine speed when turned lock to lock.
No matter which one you use, manometer or Uni-Syn, it'll get you there, and synched nicely.
I have found that doing the Uni-Syn adjustments, there may be the need to do readjustment of the vacuum closedown on the gauge often if the carb synch is really off a lot. It is just a back and forth action, set Uni-syn, check and adjust carbs, if the float goes off the scale, readjust it, keep the engine speed at the rpm you want, readjust, readjust, until the thing reads the same on all carbs. It is audience participation at its highest level, just have to get to it and do it. What...you wanted this to be an easy task...never!