I used a 95 MJ with a 50mm BBK with stock airbox and exhaust . Since you have a Uni you would need larger than a 95 MJ perhaps . Here is a jet kit with many sizes
http://www.partsforscooters.com/114-...ategory=133078
Remove the spark plug and compare the firing end with this chart to see how the jetting is
http://www.4secondsflat.com/plug_chart.html