Hesitation on takeoff
 

Hello all I'm getting hesitation on takeoff I have 20mm carborator came with 80 cc bigbore kit was 50cc stock tao tao 2020 ip39qmb stock exaust. Learning as I go I installed everthing correctly timing lineup torque setting took some time but I studied it, so after getting the backfire fixed now I'm getting hesitation on takeoff, could it be I need a bigger or smaller jet? I'm exhausted and I can't think anymore lol.