  We present an extensive analysis on several string solutions in AdS_5 x Ypq
and find some interesting properties of their energy-spin relations. Their
energy depends always on the parameter a(p,q) which characterizes these
manifolds. The range of this parameter for the string solutions is constrained
by the Sasaki-Einstein constraints that the solutions should satisfy. Hence
some string solutions we find are not valid for the whole class of Ypq
manifolds. For some of our solutions, when the maximum allowed value of a(p,q)
corresponds to the string approaching the poles of the squashed sphere in Ypq,
their energy at this limit approaches the BPS one. Thus certain non-BPS string
solutions in the whole class of Sasaki-Einstein manifolds, can become BPS in
particular manifolds. For the solutions with this property we point out that
this behavior is independent of the string motion in the other directions on
the manifold. We expect that in the field theory the corresponding generic
operators to these semi-classical strings, become BPS at certain quivers.
