Whoa dude, what are you looking at? The whole darn carb throat is only 6mm diameter. Take your air filter and elbow off the carb. Turn on your radio and receiver. Open and close your throttle while looking down the carb throat. See the drum open and close? Adjust your idle screw until the drum is about 1mm open when your throttle is closed. Now fully apply your brakes. Does this opening remain? It should or else continue to adjust your throttle screw until it does, then readjust your throttle linkage to not over stress your servo when braking.