No, but there are cases where there is no tension force on the boss too. As the piston is coming up towards TDC WOT, there is about 4,000 g of acceleration required to slow the piston to a stop at TDC, put that together with a 1/4 lb piston. When the saw is firing and a full charge being drawn in yes, early combustion and compression does off set acceleration totally or at least mostly. However the problem happens when the saw is at full throttle and the throttle plate closed, what the saw is compressing each stroke drops way down and there is nearly zero combustion, at least no combustion that makes much pressure. I did up some calcs on this before and posted some graphs showing the loading on the rod through one revolution, this showed what part of the load was from compression and combustion and what part from piston acceleration.
What Dean is saying is in line with what I have read on it. Yes the piston mass is balanced to the RPM and bore and stroke of the saw, working some of the existing pro saw designs backwards showed that in stock form the loads on the bearings were carefully engineered to be in balance with the compression force andoff set piston acceleration nicely. But start to mod a saw and bearings could certainly be pounded on by piston acceleration. But there is no RPM relationship between crank mass and piston mass acceleration between piston and crank, the faster the crank goes the faster the piston goes, so that symple geometric balance is independent of RPM changes. But the balance between bore/compression and piston mass is going to be linked to RPM so it can only be right at one speed .
Single cylinder balance is just a compromise and really only takes some of the up and down viberations and turns them into side to side viberations, if the piston is light for the crank the up and down viberations would be less and side to side the same, if the crank was lightened to match the piston weight reduction both up and down and side to side viberations could be reduced slightly. By what I have read, removing 1/2 the reduction in piston weight from the crank bells is a good start.
But for a work saw it's not going to make a hill of beans difference.