Why a single phase motor is not a self starting motor
For a motor to self start,there should exist phase shift between windings but now in single phase motors, flux produced oscillates on the same axis.This means that when you introduce another winding there will be an alternating flux.There will exist a rotation in the fluxes that will cause rotation of the rotor.The whole process is achieved by introduction of capacitors or auxillary winding or other methods.