I get a nib 660r in the mail the other day to port so I don't bother running it is just do what I always do and the damn thing just wasn't right,screw the high shut and it won't turn more than 13000 with no 4 stroke,I worked for a whole day today trying to find out what is wrong and nothing I did helped,it will not go past 13000,it finally grab a can of eather and find the damn flywheel side seal leaking.
I never thought about a seal leaking on a new saw but it was,replaced the seal earlier and I guess it came from the factory without a spring on the seal,my neighbor has been a engineer for stihl for the last 35 years and said he's heard of this a few times.
The saw was under powered but ran ok and tuned decent but would not go past 13000,I didn't think it was a airleak.