Running in a motor? every one has their own way.
If you have no expirance with that engine ask some one that runs one what the normal run in setting is approx. add a 1/4 of a turn ,set idle mixture, doing this alone will take a minute or so.
run for 2-3 min slow on ground not giving any more than half throttle.
Slowly lengthen time and speed until you can pull the plug out of a WARM engine and it dosen't pinch at the top.
too rich and you are just hammering conrod.(liquids are not compressable).
use a warm to hot plug for run in.
Like most guys say get it to opperating temp but not to much.
Don't nurse it but dont flog it, just very the rev's.
Then you can put a cooler plug in and lean off but back off at half straight for the first few serious runs. then give it to it.
Have fun