“Starter Ring Fixing Nut” 30mm Socket
Page 26-29
Looks to be the standard size socket. As long as it fits through the clutch wrench you should be fine.
http://www.iame.co.uk/wp-content/uploads/2014/01/APPENDIX-5-044-MANUALE-REVISIONE-PARILLA-X30-125cc-RL-TaG-ENG.pdf