(Portland, OR)  --  An eleven-year-old Portland boy is injured following a crash involving a go-kart.  Police say the boy was riding in a go-kart that was being towed behind a pickup truck when the go-kart crashed into a tree and down an embankment in the Rainier area.  The boy's 22-year-old uncle was driving the truck and says the boy was steering the go-kart as he pulled it along.  Authorities say the boy was wearing a helmet and a go-kart harness at the time of the crash.