  We report the structural, magnetic and electrical transport properties of
Y$_2$Ir$_{2-x}$Cr$_x$O$_7$ pyrochlore iridates. The chemical doping leads to
order of magnitude enhancement of electrical conductivity. The introduction of
Cr3+ at Ir4+ site tends to distort the Ir-O6 octahedra and suppresses
antiferromagnetic correlation. The X-ray photoemission spectroscopy
measurements suggest the coexistence of Ir4+ and Ir5+ valence states in the
Y$_2$Ir$_{2-x}$Cr$_x$O$_7$ compounds. The concentration of Ir5+ is enhanced
with Cr doping, leading to weak ferromagnetism and enhanced electrical
conductivity. A cluster-glass like transition is also observed at low
temperature with Cr doping, possibly due to competing ferromagnetic and
antiferromagnetic interaction.
