changing to athena cylinder 2006 ec125
 

I have recently changed from the normal 2006 cylinder to the athena 2013-2015 cylinder, i saw that the messico racing exhaust i had didnt fit after i changed but the legal one fitted, what unrestricted exhaust fit?

Iam really scared to do anything with the jetting dont want it to be too lean.
right now i have main jet 188 and pilot 48 the spark plug is really covered in oil and when i turn the throttle too much is goes buuuu like it gets too much air. before i changed the main jet to 188 it was 165 but 165 feels like it would be too low because in the orginal manual its 185 orginal.

sorry for bad english and writining:)

Messico racing pipe
Main jet 188
Pilot 48
Chn position in the middle

I agree a 165 is too lean. I would try a 185 or 182 main jet or raise the needle clip one slot.

As an alternative the STIC works really well on the 125 with the 38mm carb.

Another alternative is a 35mm Keihin PWK from a KX125.