(Portland, OR)  --  A man who was convicted of killing a bicyclist in a crash is scheduled to spend more than six years behind bars.  Prosecutors say 27-year-old Kenneth Britt Smith was high on medical marijuana when he hit and killed the cyclist last December in Northeast Portland before leaving the scene.  The crash killed 38-year-old Martin Greenough.  Smith pleaded guilty yesterday to second-degree manslaughter and will be formally sentenced later this month.