the sizes have to do with what size carb, if your bike is still stock, you have the stock 26mm mikuni carb with the big TORs box ontop, if your bike has been modified by you or the previous owner, you may have a larger carb, like i run a 34mm keihin carb.
most likely you have a stock carb.
if you need to send me a pic of your carb let me know and i'll PM you my cell #, you can also use it to text me when you transfer $
i'll search for the DIY vid and PM you some links