  We investigate the symmetric and anti-symmetric spin-orbit forces (SLS and
ALS) of the effective $\Lambda$N interaction derived from a quark cluster model
with the instanton-induced interaction (\III), which can reproduce the observed
YN cross sections as well as the observed NN scattering data.
  It is found that coupling to the $\Sigma$N channel enhances $\Lambda$N ALS,
and therefore that the cancellation between SLS and ALS in the $\Lambda$N
channel becomes more complete. This may be one of the major reasons why the
single-particle spin-orbit force of $\Lambda$ in nuclei is weak.
