I still can’t figure out how you are supposed to cut a length of starter rope to a 1/16 of an inch as in the specs and get it right. My knife blade alone is at least 1/8" thick and my knots can get pretty thick!
As said, load the spool with lots of rope and trim it to time the starter properly. This step may have to be redone once it has been yanked on a few times. Too much rope in this case is better than not enough as you always start an outboard motor by bracing yourself with one hand on the motor and pulling the rope with the other one. This way you can’t pull the starter handle much past your shoulder but if you stand in the boat and pull with both hands, chances are you will be rowing back to shore for repairs.