2 3/4 turns seems a bit rich I would think 1 1/4 - 1 1/2 would be a better range. These engines don't seem to be that fussy, mine ran with nearly half choke for 10 years and I didn't know it, I bought it off the show room that way. I would start with 1 1/2 turns and check the performance and the mileage, burn a tank full then check the plug, it should be a light brown. If you are getting about 60 MPG and it will do 65 - 70 MPH, you are there. If you can operate in that range I would not touch it.