These special "race only" crankcases are the foundation for the S&S Cast Pro Stock engines. These crankcases can accommodate cylinder spigot bores of up to 5.335". Cylinder deck heights are available as high as 1.750" taller than stock. This allows the use of 4.800" bore cylinders. Cam chest is a modified 1986-'90 four-speed style and is offset .850" to allow larger bore sizes. Cam chest offset requires the use of special billet four-speed style tappet guides with corrected pushrod angles, which are included with the crankcase.
Pro Stock crankcases require a special S&S Pro Stock flywheel assembly which features a big twin style sprocket shaft, .850" longer than stock pinion shaft, and special big twin width connecting rods. Must be used with special race frame. Will not fit stock chassis of Harley-Davidson® Sportster® motorcycles.
Notes:Designed to use 1991–2003 style transmission and primary components.
These cases do not have the oil return ports final machined into them. The customer is responsible for the configuration of their own return ports to fit the chassis.