I was having a sticky beak round the place to see if I could find some clarification about the subject when I stumbled upon this person's description of the effort required to effectively 'sync' the K-bike's throttle bodies at anything above idle. have a read of his comments. It's not to be done easily, me thinks. Just stick with twiddling the airscrews using a Mercury carbstick set, vacuum gages or somesuch other apparatus.
"Well, as it turns out, I did go there with my old K100RT (same throttle
body as your bike has, Vox). The reason I had to rebalance the throttle
bodies was that the twit of a previous owner had played with the
adjustment, thinking he could do a better job than the Bing factory.
What I did was to drive a big Gast high volume rotary vane vacuum pump
with a 1/3 HP motor and draw a high volume of air through each throttle
body (one at a time) noting vacuum on each one at various low throttle
openings.
It was a bitch to get right, since, slightly adjusting one throttle body can affect the others.
In the end, after several hours of work, I managed it. The result was a
smoother idle and slightly better low-throttle performance. Under higher
load, of course, there was no change in performance, but none should be
expected, since the tiny changes in butterfly angle needed to balance
the throttle bodies at closed or near-closed position, are far too
insignificant to make any noticeable alteration to airflow at 1/4
throttle or more.
My basic point above was that first, even if the throttle bodies somehow
managed to get out slightly of alignment, all it affects is idle and
maybe some low-throttle smoothness. Hardly worth the effort.... unless
one has a bike that has been previously mucked around with."
~Bob, from Vancouver
(but I dunno which one)