I'm with Gene here...run it very rich, slobbering rich for the first 5 or 10 minutes, then slowly lean it over several runs until it's just below a 2 stroke for maybe a total of an hour. After 30 minutes or so I like to vary the throttle so the load changes. One thing that has to be realised is that it's not just the fit against the liner that's being determined but it's also the fit of the ring against the bottom of the ring groove. This must be perfect to hold a proper gas seal. I prefer to use at least 20% castor oil for running in as well.
It may seem like a lot of work compared to an ABC but it's well worth it. A ringed engine can last much longer than an ABC and usually only needs a comparatively cheap ring fitted to restore it to virtually as new.