P200 engine, polini kit, sputters when changing gears & downshift

Hi folks fabs here…i have a p200 engine with the polini 210kit on it. After months of hastling, i finally got the bike running well (timing was realllly off and had to grind holes on stater more). I have on the bike:
lightened flywheel
sito plus exhaust
ported cases
did a second oversize on kit
have orig. keihin 30mm carb on it.

the bike idles well and when giving quick throttle shots, the idle goes back down well and smothly.
The problem is when i’m accelerating, pull in clutch to change gears the engine kinda „jerks“ a bit, but when i release clutch and give gas it accels well.
I have checked the needle size and clip position and it’s okay.
I have a 55 idle jet and a 130 main jet. I have not checked to see with these two (idle and main jet) are set properly. Can anyone give me some clues as to what and where to check for error? thanks
fabs