This was an old Virginia Forestry saw. Pulled the carb and cleaned it up.Got it running real good.Kinda' reminds me of my XL12.She has an awesome sound. Now here's where it gets weird.As I said I got the carb dialed in real good,set her down and she idles for about 10 min.s while I played around with a 49SP and I shut it off. Put the air breather back on and the carb goes way out of adjustment.Check and clean the filter and it's okay.Took me a stinking hour to figure this one out. What was the problem?