brendan i beg to differ. for people running a stock pipe and a 14:12 on the polini i'd put jetting somewhere in the mid-high 50s. in fact polini recommends that if you're using the stock carb on the 75cc kit that you should only go up maybe 2-4 jet sizes...and stock jetting on a V1 with a 14:12 is generally low 50s, somewhere in the 49-53 range depending on the bike.
you might still be jetted too high honestly dude. keep going DOWN from 60 jet by jet and see if the bike starts running any better. jetting may not be your whole problem, but if you can get the thing running on a 58 or 56 jet its a good start. not saying this will definitely be the right range, but its a small carb, restrictive pipe and a 15cc bigger kit. theres no need to get super excessive with the jetting.