I would be most grateful if you could spare a moment to to divulge some of knowledge re; suggested carb set up .
The spec i am running is an ET3 primavera
Polini 130 (cases ported, but barrel ports unaltered )
Rotary valve mazuchelli crank.
16 degree timing
Carb 25PHBL , D22 needle (2nd clip from top) , AqAvAs264 atomiser & 95 main jet.
Problem : engine is rapid up to half thottle then above half throttle it seems to get sluggish and won’t rev out. I’ve tried a 92 & 90 main jets with the same results aswell as two different expansion chambers (simonini d&f and sito banana).
Do I need a different needle jet? would an X3 work? I’m stumped
Ps. Plug colour is perfect