Do a plug chop to see if it is lean . Same size engine as before or a BBK . Did you check the valves as they may be tight and not opening up all the way to allow air and fuel into the cylinder . Here is a plug chart to see how your jetting is
http://www.4secondsflat.com/plug_chart.html A guide to help you check and reset the valves if needed
http://www.scooterforumonline.com/in...ic,1720.0.html