I have used Amsoil 20w-50 in a 2004 HD XL1200 Sportster/Roadster, both motor and transmission. Great improvement in motor and transmission performance, as compared to the HD brand oil.
I have also used Amsoil 20w-50 in a Victory Hammer 100 cu. in. (6) speed bike. The engine and transmission share the oil, capacity is 5 quarts. Great improvement in motor and transmission performance, as compared to the Victory brand oil.
Off topic, I have also used Mobil-1 20w-50 in the Hammer. I feel that both oils perform equally in performance and mpg. The Mobil-1 appears to be an excellent alternative.