1) The clutches on K1 up to s.n. 1056079 use an outer ring (22151-300-000) and 6 friction disks (22201-283-000) . After that the clutches use 7 friction disks (22201-300-000). All K1s use only 6 plates (22321-283-000).
2)You can scuff the plates with 400 - 600 grit paper. Be sure you sand in a radial direction (from centre to outside of ring) and not lengthwise (along the circumference). This sanding will add gripping power to the clutch but will wear the friction plates faster.
3) While you have the clutch centres on the bench, add a few more oil holes and chamfer them holes slightly. Place the holes in the grooves (not on the lands) and symmetrically around the clutch centre, drilling around the middle of the clutch centre to best lube the inner plates. Don't line them up all in a row, but a little zig-zag should allow max oiling. That will help reduce wear on the inner friction disks.