carb size
The size of the carburetor is related to the volume of air that flows through it during a given time period, which is why a larger engine needs a larger carburetor, given all other conditions (rpm, volumetric efficiency) remain the same.
Let me guess about that pocket bike engine you were refering to:
1) it isn't a stock engine, even for *pocket bikes*.
2) the engine itself has the internal parts, porting, ignition timing, and exhaust to turn upwards of seven to nine thousand rpm. (Vs the usual 4500 to 5000 rpm of the 'happy time' engines)
3) it most likely has a reed valve. (permits use of a larger carburetor, due to assymetrical (sp?) intake timing.) 'Happy time' engines tend to be piston port, which means a larger carb will cause 'loading up' when opened wide at low revs.
4) Gearing, clutch, etc work around the lack of bottom end torque, i.e. the clutch doesn't engage abruptly, but slips some to permit the engine to climb into its power band - like some kart clutches do. I suspect 'fanning' a 'happy time' clutch is a sure quick way to ruin it.
I've worked on my share of two-stroke engines over the years, welded an expansion chamber or two, jetting, timing, overhauls, ports, etc. Two books you might want, one by Gordon Jennings (out of print) and A. Graham Bell. This last is available on the net, though the downloaded version is sufficiently poor that purchase is wise if you plan on really using it.
Hope this helps some.