If you have a 7 speed on your bike, use at least 3rd gear to pedal start, and 4 is better if you can pedal it from start. If I use lower gears 1st n 2nd there is not enough force to keep the
bike going when I pop the clutch from a low speed takeoff. Once you get going and the engine pops and you keep pedaling you will see what I mean. You will get used to what speed you need to be at to get the engine to turn over and pedal assist launch. Lower gears you max out pedaling too quickly, and the engine will sputter and fail as you cant put enough torque on engine to keep it going from slow takeoff.
You want to be able to pedal into where the power band starts to grab on your engine.
Adjust your idle setting and clean your air filter so the engine runs when you pull in the clutch.