31-0001 84-91 crankcase assembly, 3-5/8" bore. Natural

S&S Superstock crankcases for 1984 to 1991 Evolution Big Twin models with 3-5/8-inch big bore are cast from 356-T6 aluminium and are substantially stronger than the OEM cases. Pre-assembled with sprocket shaft Timken main bearing races, cam needle bearings, and a pressed and line-honed pinion shaft bearing race, they include cylinder studs, nickel-plated bolts, crankcase fittings, oil pressure sensor, timing and magnetic drain plugs, and an alternator stator plug clamp screw. The ported breather design maximises scavenging and cases are clearanced for up to five-inch stroker flywheels. Sold as a set with instructions. Note: 1984 to early 1985 Evo models require a late 1985 to 1991 style cylinder head bolt kit. Replaces OEM reference 26190-73.