Welcome to the ORG.You can bring to Racewerks at alexandra they have the machine to detect which injector is clogged and able to clean it.I have done mine there happy with it,but its going to cost you.
A cheaper way is to buy STP injector cleaner or Motul fuel cleaner.
Regarding valve clearance,got to depend on the mileage and condition of your busa.
There's recommended mileage to do the valve clearance servicing in the manual.