If it has more than 1000 miles, you may want to decarbonize the motor... this involves taking the head off, so if you don't have a trq wrench, you'll need one toy properly adjust the head.. or you could use the "uhg" factor that Ree uses...
Clean the exhaust too... if it is glogged it will cuase problems...
2.5 oz of oil to a gallon of gas...
make sure the chain has enough slack.. if it is too tight, it will make too much resistance...