that's why i always say, premix is not suitable for street use.
if you're gonna premix, you'll need a big big tub, a measuring
cylinder, a calculator (or a really good head), a big spoon, some
garlic, pepper, sliced onions... erm.. oops 
anyway if u premix, it's best to finish your entire tank in 1 shot,
like they do at the races, becoz when you refuel, you get the
mixture all mixed up (pun, sue me), that and certain brands of 2t
are prone to settling after some time of idle (ie. a747)