Hi!

In a situation like this you must open the idle needle fully (much) so there is no restriction there. Eliminate all things that can restrict the fuel flow.
Then you start the engine and adjust the high speed needle at full throttle.
If the engine can hold the rpm everything is fine! If not open the low speed needle some more. If still the engine cannot deliver full rpm at full throttle something is restricting the fuel...Or wrong fuel is used, first check carb and fuel lines.
...Then set the low speed needle (idle needle).

Using the pinch method is not that exact! A much better way of setting every engine is by ear! listen to how the engine sounds and respond from there. This is very easy to do.