The butterfly's being open more will increase the Hg reading, these should only be open when the throttle is twisted. With the throttle fully home the Hg reading is set via the pilot circuit only, each must be between 230- 250mmHg at between 1150 - 1250rpm, if the reading is too high the butterfly isn't in it's rest position. This could be due to a number of factors, bad assembly, worn/broken part/s or incorrect previous carb balancing.
I my experience most owners and many stealers don't know how to balance crabs, they go straight for the butterfly screws when it's the pilot circuit that's the issue. As I stated unless they're all pulling min/max of 230- 250mmHg with the butterfly's at rest you're wasting your time. The other real big mistake onwers/stealers make is moving the TPS, this is set at the factory and it doesn't move (unless it's faulty) in operation it's a datum. They test it, it's reading over/under and they move it, that's it the datum is moved, the reason it's out (and it only works on the one carb No4) is because the butterfly/linkage has moved/worn, so no longer aligning with the datum. It's the butterfly/linkage that needs bring back to the datum, by resetting them, i.e. level of Hg, then balance all the others, 4-3 then 1-2 then 1-2 & 3- 4. Just about every TPS has been moved and in my experience just about every bike I've worked on the carbs are out of balance!