Sounds to me like your numbers are pretty much in line with what they should be on that size a prop. Sounds like your on the right track. change the carb out and let us know how it goes. post your results on the another darn ryobi post so it can add to the testing base there. as far as a slight miss now and then it could be your spark plug and it could also be the carb as these engines seem to be real mixture sensative.