Standard for the RM125M is 60T, RM125A is 57T & RM125B is 59T.
51/52T would be like adding 2 teeth to the front sprocket. Not a good idea, probably a typo.
It was probably meant to be 61/62T.
51/52T would save you gears as you'd only use 1st & 2nd but fry your clutch to hell just to get it moving. hahaha