We report a comprehensive neutron scattering study of low energy magnetic excitations in the breathing pyrochlore helimagnetic $text{Cu}_2text{OSeO}_3$. Fully documenting the four lowest energy magnetic modes that leave the ferrimagnetic configuration of the strong tetrahedra intact ($|hbaromega|<13$ meV), we find gapless quadratic dispersion at the $Gamma$ point for energies above 0.2 meV, two doublets separated by 1.6(2) meV at the $R$ point, and a bounded continuum at the $X$ point. Our constrained rigid spin cluster model relates these features to Dzyaloshinskii-Moriya (DM) interactions and the incommensurate helical ground state. Combining conventional spin wave theory with a spin cluster form-factor accurately reproduces the measured equal time structure factor through multiple Brillouin zones. An effective spin Hamiltonian describing the complex anisotropic inter-cluster interactions is obtained.
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