The fourth Standard Model (SM) family quarks and weak iso-singlet quarks predicted by E6 GUT are considered. The spin-average of the pseudoscalar η4(n1S0) and vector ψ4(n3S1) quarkonium binding masses of the new mesons formed by the fourth Standard Model (SM) family and iso-singlet E6
with their mixings to ordinary quarks are investigated. Further, the
fine and hyperfine mass splittings of the these states are also
calculated. We solved the Schrödinger equation with logarithmic and
Martin potentials using the shifted large-N expansion technique. Our
results are compared with other models to gauge the reliability of the
predictions and point out differences.