I hope you're not just starting it and letting it idle on a fresh build, idling is the worst thing you can do to break in rings. The compression puts pressure on the rings against the cylinder wall so the hatching fron the honing can wear the rings into a tight fit. You gotta ride it, it's actually good to give it some strong throttle, just don't completely beat the hell out of it or keep it at a steady rpm. When I break in a new engine I ride it around slow, but not dogging it, keep the rpms high enough that it's running smooth and not chugging at all. When the engine is close to operating temperature I start rolling into the throttle in 2nd and 3rd gear, about 1/2 throttle, getting up some speed and then letting go of the throttle to let the compression in the cylinder slow it down. Then roll back into the throttle and repeat the cycle.
That might be all you need to do, take it out and give it a good ride like I described. Most likely the rings didn't seat correctly yet because you haven't rode it to wear the rings in.
