Wiseco Twin Cam® 4-1/8” Big Bore Pistons

These 4-1/8” bore forged piston kits come complete with rings, wrist pins and circlips, and require 4-1/8” bore cylinders (case machining required). The design is similar to a NASCAR-style piston, stiff and very light. Valve pocket diameter and depth allow most oversize valves to be used without problems. Run at .0025” clearance in aluminum cylinders for street use.

’99-’06 Twin Cam® Stock 4” Stroke Pistons: 4-1/8” bore yields 107” displacement with stock ‘99-’06 (88”) 4” stroke crankshaft, retains stock cylinder height. Wrist pin centerline to piston deck height of 1.265” (center of piston has .050” raised dome, can be cut flat if desired). Please note: In 2011, this piston design changed to accept Wiseco’s new VM ring package. If ordering replacement rings, please verify your oil ring size before ordering.

This product is not for sale or use on pollution controlled vehicles.