Correct size jet to go with a leovince sp3, on a 50cc honda vision

hi i bought a leovince sp3 from this online shop , fantastic i might add. i got the exhaust through and it came with the correct rollers , its on a 1985 honda vision ne50 i have restored, i want it to run properly but that will require an up jet? can anyone help me on this ? i.e what size to go for or a rough idea to get started? thanks