You will need to fiddle around with jet sizes in the bowl type dells etc and the high/low needles in the walbro type ones. So whichever way you go there will be a certain amount of tuning involved as every motor is different depending on what mods you have.
I've only run the walbro wt603 rep as well as a ported 14.6mm stock carb but i reckon the walbro rep is the best bang for buck carby. Mine performs really well especially in the higher revs where the stocker wouldn't. They can be a bit testing in setting them up to begin with but there is the added bonus of just turning the needles to ritchen or lean it out. You don't have to go and buy a different jet every time you mod or change something.
Just my 2c
This is the one i got...
Ozminimoto - Mini Pocket Bikes - Product Detail
Its a good cheap kit. You do have to grind a little bit of the engine casings for the accelerator bracket to fit and the top right manifold bolt needs to be countersunk, but thats an easy job.
