I was so nice today I took the afternoon off. I worked on that small hickory and cleared a bunch of brush to get at it. I took a couple of videos, but the first was running an 18" bar and Oregon 91PX, and I had a heck of a vibration problem. The wood is pretty hard, but it still seemed extreme (more about that later), so I changed to a 16" bar and Carlton N1. That was a big improvement.
The saw ran quite nicely - still not super exciting, but certainly competent. I think adding the transfer access notches in the piston skirt made a noticeable improvement.
Here's the video - I think the tuning is a bit fat, but not too bad. It's mostly running around 10,500rpm, sometimes over 11,000:
The no load rpm was around 14,200rpm.
Later I looked at the 18" bar. It is a PowerCare bar, and while it's hard to see it turns out the bar rails are not high enough relative to the bottom of the trough. The bottom of the drive links have been peening the laminate center insert in the middle of the bar, and the drivers have been flopping to the sides and wedging open the rails. Both sides look the same. No wonder it vibrated some!