You want the arm to be slightly above the channel. You have to bend the arm. if the arm is too low it will restrict fuel flow. Set the arm first then do the pop off.
Pop off, low pop will not hurt you, pop that is too high will restrict fuel flow. If you find you’re sluggish coming off of tight turns and can’t seem to dial it out with the needles you would try a higher pop off.
FAA certified jet engine and aircraft technician,
Nicholson Speedway class champion 2001,
Yamaha KT100 Service Center,
41 years karting experience
Still having carb problems, and attendent lack of power, and have learned how to service the carb. Discovered that the screw holding the pivot arm in the carb was stripped, and loosening up – it was a US size – 40 something – so I tapped the hole with a 3mm tap, and used a 3mm screw, and that is fixed now.
I found this document on EC’s website, that I think is very valuable. Thought I would share it. If you page, has information on HL carb blueprinting as well.