RE: Super Tiger 90 Low Speed Needle
J3,
I have an older 90 too, and it has always been one of the most reliable engines I have ever had. It would only dead stick on me when I ran out of fuel... it had the common rich midrange thing too, but that didn't seem to hurt anything.
Try this:
Adjust your throttle linkage so you can completely shut the throttle barrel.
Put a length of fuel tubing on the fuel nipple... long enough so you can blow into it.
Open the high speed needle 5 to 6 turns.
Blow into the fuel tubing, and adjust the idle needle until air just starts to escape when you have the throttle set at an idle position (about the opening of a modelling pin). When you close the throttle barrel completely, the airflow should stop.
This procedure will get your idle needle back into the ball park, or even close to perfect once you get the hang of it, but it will need further adjustment to get it perfect.