Thxs for responding.  Agreed, old two-stroke scooters are bad news--I would never own one of those smokers that is too underpowered to ride on city streets.  The recent 4-stroke models are very much improved with computer-controlled programmed fuel injection and other emission goodies:
---------------------------------
Honda's Silverwing is powered by a 582cc DOHC parallel-twin, liquid-cooled motor, putting out a claimed 50hp (@7,500 rpm) and 37 ftlbs of torque (@6,000 rpm), Vibes from the 360-degree crank are kept at bay with twin balance shafts, fuel is injected, emissions are reduced by an exhaust air-injector and catalytic converter, and final drive is by CVT.
----------------------------------

400-600cc Scooters are tiny compared to the big Harleys and Honda Goldwings in engine displacement and acceleration performance.  But if one just needs acceleration superior to most traffic--these scooters are sized just right.  The big bikes and crotch rockets can accelerate like missiles--most car drivers have no appreciation of the unbelievable "get-up and go" these high power machines are capable of achieving.  It is not necessary to have a big bike or crotch rocket unless every now and then you wish to 'goose it' for a thrill.

Bob Shaw in Phx,Az  Are Humans Smarter than Yeast?