When you rebuild with pop up, do you use the gasket or delete it? Just bought a 272xp pop up fpr my old 61, of course will check squish, but just wondering, gasket or no?
As others have pointed out its based on my squish measurement. Im not gonna go below .018 on anything and you always want to rotate the engine over by hand fully assembled, .022 seems to be a very good spot.
If the squish allows a gasket I use it , if not it gets deleted. Recently I made an extra thick gasket for a 288 so I could use an 066 piston in it and it raised the exhaust which gave it some pep.
Honestly I don't use a compression tester on a rebuilt saw ,in my opinion its a diagnosis tool for a saw thats being checked for problems. I don't care what the compression is after I set the squish and other timing numbers , as the saw should be healthy after a piston replacement, if it feels weak after that something is wrong ! Time to stop and figure it out.
I will say that engine size will have a dramatic effect on how compression feels though, there's a huge difference between the tight squish of a 090 137cc and a 346xp! So know what your comfortable with as far as starting and using.