If you have a YZF-R125/WR125/MT125 and you don’t have it already, please grab a PDF copy of the R125 service manual and owners manual from the links below. They’re only the first gen but there’s still a lot of similarities and most of the engine stuff is the same as on the WR/MT.
Covers most/all repair procedures, also includes a few pages with every torque value needed, wiring diagrams etc
Covers stuff like how to *actually* check the oil correctly, maintenance procedures…etc
YZF-R125 Error codes:
I’m not trying to claim credit for these – very useful post on the R125 forum: