My SLT750 tops out at 30 MPH. The engine soulds like it is running right but just won't go any faster. If I get more then 300 pounds on it it will not even do 30. The RPMS are around 4500. My guess is a fuel problem but I have replaced all the fuel lines and plugs and filter. I have not taken apart the carb. Not sure if I know enough to do that without messing it up. Any other suggestions would be great.