Why do low spots matter? Light scoring? Oil film. A smooth surface creates a much stronger oil film that prevents the piston from contacting the cylinder in the first place. Surface imperfections can create pressure points. Think about how much easier you sink into snow just walking around in your boots. Now switch to snowshoes or skis and you glide right across the top. I would scotchbrite the cylinder using the Rolloc arbor and see how it cleans up just from that. New piston and ring and go cut wood.
Rolloc scotchbrite has absolutely no place in a motor. I have rebuilt more motors because of rolloc disks, and quite a few engine manufactures have countless TSB's on not using them on an engine.
Here's the last one. Done in October, 29,000 miles, rolloc cleaned the timing cover about 5,000 miles earlier. Top pic is going together.
Correct would be to measure out of round and cylinder taper. But you would need a spec of what the bore is supposed to be first to compare what you are measuring. You can cleanup aluminum transfer with acid. The piston should be replaced unless you do not care about the results or have high expectations for this saw. I prefer to use a deglazing or sizing hone depending on what the condition of the cylinder. Here is a good link with some basic info and video on the process http://www.enginehones.com/technical.html Someone people just sand or use whatever is available to clean a cylinder up and I guess it works but key is to clean that jug up after any abrasives so it doesnt work its way into any part of the bearings or rotating assembly.
+1 on the rolloc They can be good if used carefully. I rebuilt a subaru engine last year after it was at the dealer, the tech that worked on it managed create .010" low spots on the deck surface created an antifreeze leak between the head and headgasket and leaked antifreeze internally and wiped up the bottom end on the engine. Dealership blamed it on the customer for "lack of an oil change" thought I was going to be caught in a quagmire there.
Lots of ways to tackle this (or not)...lots of opinions. I'm not one to mention other sites on here, but nearly all other chainsaw forums have beaten this topic to death with a couple overall conclusions. Good luck!
This is a bit different. You aren't using a Rolloc disc, just the arbor and a regular squarish piece of scotchbrite to shine the carbon right off that cylinder and it will remove any light transfer from the cylinder walls. Heavy transfer will have to be dealt with via sanding or acid ( I no longer even try the acid for cylinders ). Of course you are not putting the engine back together without rinsing the cylinder clean of all the scotchbrite dust it leaves behind. The technique I am referring to starts at about 1:15 or so.
The late model 350's ran so good, the Swedish mother ship had to do something to broaden the gap between it and the 353... Enter that stupid dished piston... Now we know... "The rest of the story"
I appreciate all the different opinions about what is and isn't appropriate here. MM's oil film reasoning, combined with the prospect of a performance gain with a flat-top piston, is enough to convince me. I'm not sure whether I'll ultimately sell this one or my 55 Rancher, so it makes sense on a number of levels to do it right.