Originally Posted by
WingWrecker
If I understand correctly then it sounds like the return spring isnt bringing the carb slide back to idle. Is there a spring connected to the carb slide on one end and connected to the high speed needle on the other end? The throttle servo wont push the carb back to idle, there should be a spring that holds the carb shut and the throtlle servo pulls against it to open the carb.
Is this what you mean?
The servo most certainly should be returning the slide back to the closed position; it uses a small spring (similar to something you'd find in a pen) on the throttle arm vice the spring used to prevent runaways.
It sounds like you're setting the idle position while holding the brakes. I'd start by centering your throttle trims, pull the servo horn off, and re-apply so the carb is sitting in the idle position. Adjust the throttle and brake linkage from this point for fine tuning.