I think he means OS 46 FXI. that's what ships on the Nexstar.
You can download and view the manual for this plane here:
http://manuals.hobbico.com/hca/hcaa17-manual.pdf
They say the engine is pre-run at the factory. This doesn't mean that it's broken in. In my experience with this engines, if you run them rich for the first 10 tanks or so you'll be fine. Then lean it out so you have the faintest smoke trial in the exhaust and the engine will last for a very long time.
Ken
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