I wouldn't bet a plug nickel, but say the original motor was a star conected motor and you added three capacitors from each phase to a common point (not the neutral of the phases) and sized the capacitors using the relationship that no load apparent power equals the reactive power to be provided by the excitation capacitors. Then I don't believe you would need the start capacitors. For a 2Kw, 420v, 4 pole, 60hz, three phase motor that draws 3.5 amps this figures out to be ~40uF
(I would not take this advise if I was found of the motor or faint of heart)