**It's an old wive's tale in this hobby that engines require extensive break-in before you can get a reliable idle or a good running engine.

Just installed a OS LA40 in a funfly. Flew it after about 10 mins of ground run. But had a hard time maintaining idle or constant RPM for maybe the first 8 or 10 flights. Had dead sticks, needle needed to be regularly adjusted. But once its settled in its great..