Your best bet would be to find one of the many how to jet a bike threads and read it. And, while you should check the reeds, you will not necessarily need to replace them.
if you use after market reeds-fmf/boeysen- you need to re jet -because the new reeds do not use the stock reed stops -just follow the instructions in the package
most of the time its just a main jet change
as for re jetting it stock why would you?
try good oil-40:1 - i use klotz
How about because almost no bike ever comes from the manufacturer jetted right for each person and location? I've yet to own a bike between my bikes and my son's that the stock jetting offered the best performance from the bike.
Trying to fine tune an engine using the premix ratio is a waste of time. Pick a ratio and stick to it and then adjust your jetting properly to fine tune the performance of your machine. Sure you might get it to stop fouling plugs by changing the ratio and if that's your idea of tuning the engine for optimum performance far be it from me to stop you.