  In this paper, we discuss the properties of the generating functions of spin
Hurwitz numbers. In particular, for spin Hurwitz numbers with arbitrary
ramification profiles, we construct the weighed sums which are given by Orlov's
hypergeometric solutions of the 2-component BKP hierarchy. We derive the closed
algebraic formulas for the correlation functions associated with these
tau-functions, and under reasonable analytical assumptions we prove the loop
equations (the blobbed topological recursion). Finally, we prove a version of
topological recursion for the spin Hurwitz numbers with the spin completed
cycles (a generalized version of the Giacchetto--Kramer--Lewa\'nski
conjecture).
