The spring is there for 2 reasons, to bring the throttle back to idle on the chainsaw and to keep the throttle disc centered in the venturi..If you take the spring completely off the throttle disc will vibrate in the bore at high rpm and wear it out, along with the carb body itself...Extreme wear will result in enough space around the disc to let fuel in when the throttle is closed, so the idle will be higher than it should be...The spring should be left in place but if you don't want the tension the ends can be clipped off..That way the spring will still keep the disc centered but will not put a load on the servo...There is a clip on the opposite end of the throttle shaft that the spring keeps tension on to keep the disc in the middle....