<a href=showthread.php?s=&postid=13741751#post13741751 target=_blank>Originally posted</a> by dngspot
What changes the degree of rotation are the arms on the motor and the down tube. If you increase the motor to the same arc as the down tube arm you should be able to get 180 degrees but, will also go over center and lock up the motor. This stuff works sort of like sprockets on a bike, the closer you get to the same radius the closer you get to the same amount of movement per stroke. Shorten the motor arm and you move less. As for the down tube arm make it shorter, more movement and longer less movement. The tie rod is like a bike chain if it is too long it will push the down tube arm at it highest point and lock the motor. To short and it will not allow the motor to complete rotation at it lowest point. I set mine up by moving the motor arm to the lowest point away from the down tube arm, then rotate the down tube arm so it is closest to the motor and fit the tie rod to the arms.
I hope this helps.