http://www.torreypinesgulls.org/Radios.htm

ATV = Adjustable Travel Volume, EPA= End Point Adjustment. Two ways of saying the same thing, how far each side of neutral the servo will move with full stick deflection.

Proper mechanical setup will have your linkages and servo arms set up so that you are close to 100 and equal on both sides in most cases. For example lets say that your throttle linkage is binding at 100/100 atv. You lower the atvs till it doesnt bind and find out that you are 60/60, that says you are too far out on the throttle arm, too far in on the servo arm or a combonation of both but your linkage is the right length and everything is centered.

If you end up 110/80 then you have to work on your linkage so that they are both 95 or close to it, do this by adjusting the throttle arm position, the servo arm position and or the length of the rod. The quick way to setup proper linkage length is to measure from the center of the servo screw to the center of the pivot (say the middle of the throttle arm in this example) with calipers and make sure that your linkage from center to center is the same length, the distance from the center of the servo screw to the ball is the same as the center of the throttle linkage to the ball and that both arms are 90 degrees to the linkage at 50 percent throttle and there is full throw with no binding at either end.