PM sent for the FSM's
A manometer is measuring vacuum or negative pressure, has nothing to do with air/fuel ratios.
Synchronizing carbs is is adjusting the throttle plates to be open exactly the same amount at idle.
Balancing carbs is to adjust the throttle opening at higher RPM to match, similar but not the same thing.
On the SOHC carbs the linkage is tied together so synchronizing at idle is the same as balancing at higher RPM.
On bikes that have dual throttle cables, linkages can operate independently, balancing is done at 2,000 or higher RPM by adjusting each cable so air flow is matched.
On to mixture setting:
With the engine hot after riding some and parked on the center stand set the idle speed to 1200. Never over 1300.
Pick a carb and adjust for highest idle speed, you may have to re-adjust the idle speed while doing this to keep it low enough. Once that's done go to the other carb and repeat. Repeat on both one more time. Go ride a few miles to cool the engine down and recheck the mixtures one more time. You're done.
Honda list "turns out" in the FSM for mixture. Consider that as a starting point for setting the mixture.
If there are limiter caps on the mixture screws cut the tab off of them or the tab on the float bowl.