How much horsepower is produced by a 1250 cc harley Davidson sportster?

Depending on what other mods have been done to the bike a 1250 cc can produce anything from 80 to 110 hp. Less and more is certainly possible. Cams and exhaust play a major role in this equation, as well as heads and headwork, and generally speaking more hp means more rpm, and less torque on low rpms.