re: machine dating, im not really sure how to tell the difference between an early series and a late series, is there anything that would give it away?
As far as fuel, i have been running it pre mixed so i know that i have not been running it without oil, but who knows what the previous owner did

I still have not checked the piston via the exhaust port (but will do tomorrow morning). would a pic help you guys out or will signs of distress be obvious to even a layman as myself?
again, thanks for all the help guys!