Generally... My definition of "rich" for break-in is about 4 clicks open from max RPM on the main needle. (just over 1/8 turn if you can't feel the clicks)

If you get it right... appx 3 min into the engine run the rpm will change SUDDENLY. Its practically always a reduced rpm due to the piston seating and... it goes richer. (needs the needle closed as much as 3/4 turn)

Before doing the break-in... check internally for filings and mold flashing. Remove backplate, pull the carb. Flush a little fuel through. Hold the carb down firmly with your thumb as you tighten the retaining nut when you reassemble.