OK, I have the problem with my 94 RM 125 narrowed down to a carb issue. If I drop the needle to the last clip, turn the idle screw in all the way and back the air screw almost all the way out, it runs pretty decently. I checked for plugged jets and passages and found none. I cleaned the carb up again and am about to put it all back together. Is there a base setting for the air screw and such? How about float settings? It is like the bike is running extremely rich. It has 172 main jet in it, I don't know what it came with stock though.
Joe

With the stock 36mm Mikuni:
MJ. 180
PJ. 50
AS. 2 out
Needle R1469MS 3rd groove from top.
Float Height 16.0 mm measured from the float bowl gasket surface to the top of the float.

Thank you very much. Odd thing though- my bike is supposed to have a 180 mj, but it has a 172 (don't know if it was changed or not) and I had to DROP the needle all the way to the top notch to get it to run half decent. It was running so rich with it even up one notch that it would not even come into powerband in 1st gear or free rev in neutral. In 2nd and up with more of a load on it, it would pull ok though. I'm stumped here. I even have to keep the idle screw almost all the way in for it to idle. Any thoughts? Thanks.
Joe

Actually, I just realized you said Mikuni- the bike has a keihin (sp?) carb on it. Did someone maybe change it out, or did they come with both?
Joe