It`s just the throttle slides that need balancing.
Not too hard a job.
There`s a spring loaded adjustment screw in the middle of the throttle linkage at the top of the carbs.
Need to take the tank off to access it if you`ve got the standard airbox fitted. Will have to rig up a little fuel tank.
When the bikes idling, just tweak the screw 1/8 to 1/4 turn at a time and see how the bike reacts.
Should be easy to achieve a good balanced idle from both cylinders.