At 12,000 RPM's the piston is coming to the top of the hole well over 100 times per second. They will be well seated in pretty quickly, trust me on that deal.
I work on power equipment (among other things) for a living. The CS-490 is pretty "weak" right out of the box, and a tad better after removing the limiter caps and adding some fuel, and modifying the restrictive muffler.
I just bought, modified, correctly adjusted and sold one.
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I ran a couple of tanks thru it and put it up for sale. It cut pretty well, but not even in the same league as my CS-510 or either one of my Husqvarna closed port 55's, and certainly wouldn't hold a candle to a 346XP.........IMHO.......Cliff