Here are some 31mm
Do you know what width you need or what stem length or offset you need etc? What about the forks, leading axle or non leading axle will determine what offset your should need. I am sure there would be plenty on ebay.
Yamaha IT-125 G (80) are 32mm according the my source of the below info
31 Honda CR-80R (82)
31 Honda CR-80R (83)
31 Honda SL-100 K (69-70)
31 Honda XL-100 (74-78)
31 Honda XL-100S (80 From 5103464)
31 Honda CB-125TT (90)
31 Honda CR-125M/M1 “Elsinore” (74-75)
31 Honda MT-125K (74-76)
31 Honda SL-125 “Motosport 125? (72-73)
31 Honda TL-125K “Trials 125? (73-75)
31 Honda XL-125K/K1 (74-78)
31 Honda XL-125S (80 From 5005876- 82, 84)
31 Honda XL-125S (85)
31 Honda CB-175K3-K7 (69-73)
31 Honda MR-175 “Elsinore” (76-77)
31 Honda SL-175K1 (71)
31 Honda CM-185T “Twinstar” (78-79 To 2111990)
31 Honda CM-185T “Twinstar” (79 From 2111991)
31 Honda XL-185S (79-80 To 5006890)
31 Honda XL-185S (80 From 5006891 – 83)
31 Honda CB-200T (75-76)
31 Honda CM-200T “Twinstar” (80 To 2012204)
31 Honda CM-200T “Twinstar” (80-82)
31 Honda TR-200 “Fatcat” (86-87)
31 Honda XR-200 (80-84)
31 Honda CB-250 “Nighthawk” (91-04)
31 Honda CM-250C “Custom” (82-83)
31 Kawasaki KX-80 C2 (82)
31 Kawasaki KX-125/ A1-A3 (74-77)
31 Kawasaki KZ-200A1/A2 (78-79)
31 Kawasaki KZ-250D1/D2 (80-81)
31 Kawasaki KZ-250L1 “CSR” (82)
31 Kawasaki EX-305B1 “GP” (83)
31 Suzuki SP-100 D (83)
31 Yamaha DT-125 E (78)
31 Yamaha DT-175 E (78)