Original sentence: 1991 and newer models have five speeds; 1990 and earlier models had four speeds.Incidentally, the cam followers used in the Sportsters, K models, big twin side valve models, and the side-valve W Model series were a slightly shorter version of the followers used in the larger motors, but with the same 0.731 inch diameter body and 0.855 inch diameter roller follower since 1929.The longest jump made by Knievel on the XR-750 was 133 feet at Kings Island in 1975.The riding position and 25.3 inch seat height of the Nightster are the same as those of the XL883L Sportster Low.XL, Evolution (also known as the "Evo"), 1986–present: 883 cc, 1100 cc and 1200 cc Evolution overhead-valve engine, alloy heads
Edited sentence: Incidentally, the cam followers used in the Sportsters, K models, big twin side valve models, and the side-valve W Model series were a slightly shorter version of the followers used in the larger motors, but with the same  diameter body and  diameter roller follower since 1929.Models since 1991 have five speeds; 1990 and earlier models had four speeds.The longest jump made by Knievel on the XR-750 was  at Kings Island in 1975.The riding position and  seat height of the Nightster are the same as those of the XL883L Sportster Low.XL, Evolution (also known as the "Evo"), since 1986: 883 cc, 1100 cc and 1200 cc Evolution overhead-valve engine, alloy heads