i have a 686 and am running a purpule spring and 14 gram weights. with a machined sheave. i am getting a little shift at about 43-45 mph but still pulling through it. my 2 cents. and also about 53-54 in the dunes.. with stock tires and ss108 wheels
That will all depend on the specs of your motor....a stocker 14g rollers and an orange spring......a built motor will depend on a few things, Motor, tires, terrian, riding type.
for all around I prefer the wet clutch, for short course the dry clutch is the ticket. If I raced Desert, I would also use a wet clutch with sheave with 16g weights for the "overdrive" factor for motor longevity.
Jim's recommendation is a great start for a basic rhino. Everything else from there is determined by your motor and Main riding.