The S&S 555 cams is for 74 - 100 inch engines with 9.5:1 to 11.5:1 compression ratio. It provides a broad torque curve from 3500 - 6500 rpm using ported stock heads or S&S heads. Requires spring spacing and normal clearance check and will work with either solid or hydraulic tappets. Requires cam lobe clearancing when used in stock crankcases. 3,000 - 6,500 rpm. Fits engines in 1991-Up Harley-Davidson Sportster and 1994-2002 Buell models. For 2000 and later models, 1999 and earlier style pinion gear must be used, available through S&S. S&S Part #: 33-5084