Delivered a half cord of wood to my daughter this morning, then made some progress on that 660. The carb linkage gave me fits, hate it, way different than a 440 or 460. I think putting it all back together will be a PITA.
Also, did not like those big ears on the carb side of the intake boot, way bigger than the ears on a 440/460, but the cylinder side of the boot is larger. IMO, where the air flows past those ears is the most restrictive part. May trim the boot a bit and flatten them ears a little. Any one else ever mess with them? Don't recall seeing anything about it.
The motor vac tested just fine, but I may have found a cause for what happened. Seemed like there was some saw dust in the carb and snorkel, I'm wondering if they did not tighten the air filter enough, and the additional air would help with the "lean".
As you can see from the pics, only the exhaust side of the piston was cooked, the other side looked like new. Even the spark plug looked like it had a rich and a lean side! All of the bearings seem very smooth and very tight. Spoke to the owner again tonight, and he confirmed this saw has very low hours, and the limited wear on the sprocket seems to confirm that.
Was able to clean the cylinder up quite well (Thanks Randy), there is just a tiny scratch above the exhaust port, but you can't even feel it and I don't think you will know it is there.
Tried to order parts today, but instead of having a Labor Day sale, the local dealer was closed.