Correct (I believe!). The shop manual states that the mixture is controlled by the air screw -- and the slide valve's cutaway -- up to ⅛-throttle. It doesn't say whether or not the jet needle has any effect at that throttle state.The lowering and raising of the needle does not have much effect on the idle and lower end of the throttle range. Is this correct?
I'd be inclined to experiment: go up to a 125 main and run with the needle on the middle notch. Clean the plugs and allow the motor to idle for about 10 mins, inspecting the plugs afterwards.
We've been here before: warm up the motor via a short ride>allow it to idle>turn the air screw in until the idle falters (rich)>then turn it out until it falters again (lean), counting in ⅛-turns>set the air screw back in again by half that count. Repeat para 2, sentence 2.