Last time I also mess up setting the needler. My friend teach me how to adjust it. Below are the step:
1,rich all the needler - low, high and make sure your engine can ideling
2, lean the low speed needler until it can't choch out. Mean when u press full throttle, the car can accelerate very fast without hessitate but make sure check the temp every time you lean the needler. Make sure have white/ blue smoke.
3, if u done set your low speed, now set your high speed needler. Lean it until u feel your car are very fast, make syre check the temp.
4, done high speed, set your ideling.
5, run your car for few laps and stop your car at your front for ~10 second and press full throttle see is it accerelate fast. If it still hessitate, than lean some more on the low speed.
1/8 a turn and one needler at a time.
Hope to hear a good news from u.