Ideal crusing rpm

[Rhompin45]

As it it when I'm going along at 50mph my Rpms are at 6200 if I go wot its about 58 mph at around 7200 rpm. I'm not looking to race this thing but I am think I need new variator weights since they are getting old. I don't know if I should go maybe one size lighter to slightly raise the rpm or just get the same. I want the motor to last so I don't want to go to high but it's just as bad for a motor running to low of Rpms so what's the sweet spot of these motors? As I am excelerating the Rpms go up to 5000 at around 25 maybe and increase slowly from there.