Is it possible that some saws die because they are ran dull causing bar/chain friction, and impact/vibration, as the dull tooth hits wood, that destroys the pto bearing. Then a leaky seal causes burn down, either from the loose bearing, or the seal fries and the bearing goes loose. The order doesn't really seem that important. The result is the same. AND
Is it possible that some saws die because they are ran dull until the fines build up in the filter until it goes lean on oil. As fuel/air is reduced by clogged filters until the amount of oil per rpm if you will shall be reduced whether your at 50/1 40/1 or 30/1. The engine will run hotter with less fuel going in the cylinder weather the mixture is correct at the carb or not. These are air cooled and perhaps more accurately, fuel cooled engines. Then lesser volume of oil has to work harder at a higher temp. Perhaps then you would see a fried exhaust side piston.
Less air, and less fuel, and less oil, even if it sounds rich as the air fuel ratio is now a lower ratio with less air velocity. Sure when the mixture hits the cylinder theirs more fuel than air, but how much total charge is getting in with less velocity at the transfers. This would be worse on a compensating machine, not better, ie compensating carb's and at/mt. As you have less over all flow per combustion event and less power and much less cooling.
And why not both sometimes. Sometimes stupid brakes in more than one way. It is more likely than not, not a single path to destruction. But several converging paths of poor decision. 50/1, clogged filters, ham handedness, dull chains. Just plain stupid
What can be agreed is running a dull chain is stupid, your likely to burn your piston, and maybe a cylinder. You can guess about the link, or you can tell the short truth. Running dull chain is bad mm kay. So is riding a bike on a flat tire. Maintenance is its own reward. Like they say. If you got 6 hours to axe down a tree spend 4 sharpening the axe.
This is all my opinion. Please tell me how i'm wrong. I'm just trying to learn like everybody else. As my final thought, doesn't rpm tend to kill the flywheel bearing first, not the pto. I'd be inclined to believe that heat soak, impact of dull teeth on wood, and higher rpm, work together to toast the pto bearing. Not just one lone terrorist, but a cell if you will.
