The carb itself works fairly good, the problem was the bushing that sized it down to the intake. The bushings were made of who knows what, it would fall apart in some cases. It has a choke jet also, the CNS uses a thumb lever on the handle bar to open the jet to richen the fuel mixture for starting. The five 2010 kits I bought in a lot all came with the CNS-2, three have been replaced with the n/t including one of mine.
My bike did have a higher top speed with the CNS-2 over the nt by 1 mph, but the nt is in my opinion much better suited for the 48 and 66cc engines. You can adapt a lot of carbs to fit but if you don't have the experience with tuning its very hard to get right, like crassius said.