Brand new single speed bike has a skip in the free wheel motion or make a click noise once every rotation of the tire
After a month the the freewheel did not improve so I bought and installed a new Shimano freewheel.  The results were night and day.  Gone was the knock when pedaling and the warble of the back tire was gone as well.  

The OEM freewheel was like dog excrement and the new Shimano is like pedaling on butter.