hmmm... didn't notice this the first rebuild....
but there are a series of tiny holes on the bottom of the carb throats..
4 of them in a staggered pattern.
you can use the sync rod and eye-ball the closing of the butterflies using them as a reference points.
I'll use the manometer for final adjustment... but this should be pretty close.
if the bike is running when you pull the carbs, you should be fine as long as you don't disturb the synq rod when taking it apart. if the rod is really hard to turn & you want to clean up the threads, then set it on a board, put some finish nails thru the holes, loosen the lock nut & count the turns to make it a little tight. then when you reassemble the rod, reverse the procedure to get it close again.
if you have calipers, you can measure the rod b4 you take it off & set it to that length upon reassembly.
i'm sure there are lots of other tricks out there too.
--Lucky
perhaps I should expound on my method...which takes into account doing everthing that Lucky said "wrong" (as always...bottom signature line applys)
I had to disturb the sync rod because it had to be torn down to wire wheel the threads to remove rust and apply anti-seize so future adjustments could be made.
when you separate two carbs held together with three brackets and 10 screws (for dipping and rebuilding)... there's little chance to get them aligned backed to exactly the pre-measured values
by holding the rear butterfly open to the first of those tiny holes
(by hand, and having the rear linkage arm connected by the sync rod to the front butterfly linkage arm)
it's simply a matter of turning the syn rod in or out to match the front butterfly to the same first hole...
quick, easy, no measurements needed... and yeah... you still get the same little bit of movement when you tighten the nut just like with the monometer...
again... this is just to get ya close so when you put them back on...., it's close
same way i do it,, just like gene berg carbs for a VW but i cheat, i put a fine "P" pin into the hole ,to hold it open,,, ( my fingers get tired quick) then a touch up with manometer to dial them in,,,, quick easy and will hold up if you have to ride it for a while to get to a meter setup
I set initial sync by turning the idle screw out until both carbs bottomed. I then moved the sync rod until there was no pressure on it. It gets easy to turn. Then idle it up and sync it. I was close enough to leave it alone.