The spring arrangement you speak of was used by many manufacturers. Briefly, the same secondary was used with many engine/gear ratio variations. To accomadate the differant shift point requirements the spring tension is varied by selecting different holes. Using the hole that applies the least ammount of tension causing shift to begin at lower RPM. Which hole to use? Depends on the factors mentioned above and the type riding you do. I'd start 1 notch up from least tension. Yeah it's work to change the setting but, even factory settings were just a good starting point. Good luck!