Did the run in today, I had an 18-24" oak blowdown on a side hill,so I was able to work waist high, I ran the saw wide open for 1 tank of fuel to let the digtal fuel system self calibrate. I then check the restart on the machine while it was hot, turned on the choke, push down to disengage choke and set high idle,tickle it a few times and off she went.
I stopped by a buddies of mine who is timbering nearby to let him have a run at it (had to show it off,and share the technology as he lives by the timber), by then the machine had cooled off as I spent some time with the 51 working some old log cluttering up the ground where I was working. The 550 fired up well, but seemed to have some lag at times when he used it, it stalled twice (Was outa gas), Refueled it, then once he warmed it up and stopped reving it up, it seemed to improve. He was fast on the throttle and the machine seemed to lag until it stalled. We talked about it and he said the first week or so on a new saw is working out the kinks, so with the self adjusting digital, we seemed to think it will improve over time,based on the short improvments we saw while he was running it.
Compared to the 51 it like a butter knife versus a steak knife when it comes to cutting, my 51 has a 3/8" chain and 16" bar, versus a .325 18" bar on the XP. The XP is also more ergonomically friendly, very narrow and much more nimble to wield around while cutting off branches. My 51 felt like a brick compared to the 550, big and lacking feedback you could say.
I am excited, but have to say, it ate through the first tank of fuel in no time, maybe I lost tract of time with my new saw,I recon I made about 18 cuts on that blowdown, only wacking off 4" sections as I wanted it to calibrate and keep it on the pipe with little idle time.
I think I made the right choice and will give it more action tomorrow of this weekend.
Typically when I adjusted the 51, I would lean it out, then back it off the high side so it would not run maximum RPM at full throttle,then set the idle. It would bog under load on a buried 18" oak,and you would have to either let up on the saw even though it was feeding its way through the cut, or change the angle of the bar so the face was not in full contact (Walk it through). The 550 has more RPM to offer and I could not detect much change in the RPM when buried ( If I walked it, it screamed,maybe another 2k RPM),it pulled all the way through, after each cut, I lifted the throttle for an instant, then went right back in under full load. It also seem much quicker off the bottom for limbing than my 51.