… A Sport-Twin is a sportbike with a V-Twin engine (Aprilia, Buell, Ducati, KTM...etc). There are some Japanese V-Twins also, such as the Suzuki SV and the Honda RC-51 http://californiaharleydavidson.com/ http://californiaharleydavidson.com/forums/forumdisplay.p... http://parts411.com/ http://ridersreviews.com/ http://Motorhelmets.com. Who should join? Anybody who rides a Sport-Twin motorcycle! Who shouldn't join? Anybody with a typical in-line 4 motorcycle, which is a majority of sportbike ri …