lol!! You still haven't answer my question, did you seal the fuel line from tank to carb and banjo fitting? What air gap? Does it start with one bubble and accumulates more? Air bubble caused by sudden acceleration. That's where bubbles are formed. Air gap too lean(Too wide) on HSN. Speed the servo too quick, Stock TX are common with this. Tuning 98% of fish egg bubbles. It'll dissipate after a few laps. Maybe too lean on HSN, LSN and too high on idle speed.