Thank you very much for your information showing each motorcycle stall to be 10 ft * 4 ft （3 m * 1.2 m). These stalls should be big enough for most motorcycles.
Conversely, "traditional" Taiwanese motorcycle parking stalls are just about (2 to 2.5) m * (1 to 1.5) m per http://commons.wikimedia.org/wiki/Image:TW-Art190.2.png obtained from official source, so many larger motorcycles are asked to park in car stalls there. Taiwan disallowed importing motorcycles >= 150 cm^3 for some time, until joining the World Trade Organization.
I do know that motorcycles may not protrude more than six feet (1.8 m) beyond the curb against which they are parked in New York City and http://www.nymstf.org/TipSheet-NYC_Parking.pdf has to be corrected for this. I do not consider it discriminatory as there are not always wide vehicles parked nearby. Excessive protrusion may result in being knocked over. The only time when motorcycles may protrude more than six feet beyond the curb should be in case of marked parking areas and stalls.