Carburetor for a CCW

[ProDigit]

I'd start with a PZ30. They're only $25, and easy to get.
Your jet sizes depend on a variety of things, like exhaust system, air intake, elevation etc...

If your bike ran fine before, just use a hacksaw, and saw off the bottom of the oem carburetor. Get a carburetor drill set, to measure the carburetor jet sizes.
Then measure the jet sizes on the new carburetor.
I've noticed that quite often the jet sizes built in the carburetor may say eg: 45 pilot, 110 main, but may actually be off by a few digits compared to a jet kit.

Using a PZ30, allows you to get as close to OEM as possible.
Some bikes have clearance issues with different carburetors.
The benefits of a different carburetor are minimal, unless you really want to eke out the last MPH of top speed.
Quite often carburetors like nibbi, Mikuni, or other, use different measurement units. So their jet sizes may differ from the PZ.
They might also be larger in diameter than the PZ30 (which is exactly 30mm), which may help top end, but may make the bottom end (idle) suffer.

I haven't yet found an in depth review about the differences in performance between all of them, but it's pretty unanimous. Larger mm carburetors run richer, and have better top end. Smaller carburetors run better MPG, and idle, at the expense of worse top end.
And somewhere, your bike's engine can only take so much top end. So replacing a PZ30 with a Nibbi 30mm may, or may not get you more top end.
Every brand is basically a different size. Size being the determining factor on top speed, or good idle.

I see no reason not to go with a PZ, unless you really notice awful performance, which in most cases can be corrected with the correct jet sizes.