Looks like someone replace the OEM oil drain bolt
If you need the oil drain bolt 92066A/ part #,92066-1174 PLUG,OIL DRAIN,12X15 I have a few extra ones laying around, PM me your mailing address.
It's a common size at 12x15
Don't forget to pick up several spare crush washers for the drain bolt
Kawasaki 92065-097 GASKET,DRIN PLUG --- GASKET,DRIN PLUG, GASKET,DRAIN PLUG, GASKET,12X22X2,DRAIN PLUG, GASKET,12X22X2, GASKET
Pretty common part, you should be able to find at a competent parts house.