Rubber-mount rigid frames for Sportster drivelines All of the OEM engine mounts simply transfer over to the frame, permitting a quick and easy build of a great-looking custom Frames feature a 1-1/2" diameter backbone with 1-1/4" diameter downtubes, and require a special Round oil tank 741-052 and mounting bracket 7400270 (sold separately) 30° rake, 2" out, 4" up