It takes a good ear to really get the pinch test right.

You probably already know this, but let me explain again just in case.

After starting and allowing the engine to come up to temp, (keep the glow driver on while you do this). Add a bit of throttle and remove the glow driver. Slowly go to half throttle, then to full throttle, let it run there for a few seconds, then back to idle. It should run fine.

Go to full throttle, the quickly pinch and release the fuel line at the carb or just behind it. The engine should increase RPM a slight bit then return to normal right away. This will sound like a slight change in the note of the engine. If it does not do this, or if the RPM go up quite a bit then it will need some adjustment. Let the engine go back to idle and try it again. Once the engine has reached full throttle RPM, add about a 1/8 turn more rich and pinch off the fuel line. If it sounds good, return to idle. You don't want it to sputter but to run cleanly at full RPM. If it is to lean, it will immediately cut out so you add more fuel. Once you get the RPM to increase, make slight adjustments to peak out the engine RPM by leaning it out a bit while doing the pinch test.

Once you are done with this, the high end is reliable.

The low end, well, that's a bit different. A good idea of how it is performing is to quickly go to full throttle from idle and see if it hesitates in the transition. Keep in mind that there may be some excessive fuel in there, so go to full throttle to clean things out, then back to idle, then add throttle quickly to see if it hesitates. You may have to change that low end setting (My OS engines have a little adjustment screw located in the spray bar of the carb on the opposite side of the throttle arm. It takes a very small flat blade screwdriver and SHOULD BE DONE WITH THE ENGINE SHUT DOWN!!!). Only make very small adjustments here, then restart and see if you improved that transition from idle to full. If it improves, then you may be set. If you need more, then do it over again.

Good luck.

DS.