Hey guys and girls who know their way around a phbg carb! I’ve recently upgraded to a 19mm with an 18mm intake on a polini 70cc kit. The bike is a ‘78 Garelli GranSport. Up to about 1/2 throttle, maybe a little over, it runs top, it runs perfectly. Once I hit about 40mph and am in the top end of the throttle, it starts bogging out. It usually needs a moment to recover and figure itself back out if I go into that bad zone. If I hold throttle all the way open, it bogs down, and then does a weird revving thing where it slightly revs up and down but goes real slow. I’ve tuned and returned my gas/air ration screw, set my idle jet (42), and changed my main jet everywhere between 86-94. I have the needle on the second leanest setting.
I’ve checked for airleaks, all seems to be good. Timing should be right on the mark. I have an estoril sidebleed pipe and a high flow filter on the bike. What am I missing?!
Any help on where to go from here would be amazing.