The crux of this article is to analyze the contribution of the preequilibrium reaction process to the production of residues in the low energy heavy-ion reactions. The production cross-sections of a few radionuclides produced through the 3n-emission channel have been measured from the 7Li-, 11B- and 12C-induced reactions in the 89Y and 93Nb targets within the energy range of ∼2.4–6.4 MeV/nucleon. The measured excitation functions have been analyzed by comparing them with the statistical nuclear reaction models, based on the equilibrium and preequilibrium reaction mechanisms, in the framework of ALICE91 and EMPIRE3.2.2. The result shows that the mixing of equilibrium and preequilibrium emission of light or cluster particles is essential for the better reproduction of the measured cross-section data. Variation of the preequilibrium fractions with derived energy parameters has also been demonstrated.