  The two-particle decays of B_c^+ to psi pi^+(rho^+) and B_c^+ to eta_c
pi^+(rho^+) are considered in a way taking into account a soft binding of
quarks in the heavy quarkonia and a hard gluon exchange between the
constituents at large recoil momenta of psi(eta_c). An approximate double
enhancement of the amplitudes is found because of the nonspectator t-channel
contribution.
