I had the exact same symptom and I’m in the Komet Sr class. After trying several carbs, and at the recommendation of Franklin Motorsports, I put on a new coil and the issue was taken care of. The kart now had power like I’ve never had before coming up through the rpm’s and also previously, during the pre-race formation lap, the kart could barely stay running. Now, it’s no problem to run that slow of a speed with the needle at 1 1/2 turns approaching the green flag. Also, make sure the ground strap from the coil to the motor is tight.