HyperFormance
Street Big Jugs

The narrow valve angle, shallow combustion chamber Evo® engine has launched our favorite marquee into the millennium. Aluminum through-stud Evo® cylinders are adequate for normal, relaxed, riding, but aluminum expands when heated (Iron does not). The consequence is that aluminum cylinders grow taller as they warm up, reducing compression and making it virtually impossible to maintain accurate valve train clearances with solid lifters. Poor ring sealing, and a direct loss of combustion pressure (power) can result from hot-rodding an aluminum Evo beyond its thermal and structural limitations. This is where Iron comes to the rescue... The attributes of Dimensional Stability, High Tensile Strength and Durability are legendary. Our Big Jugs™ are machined from pure Ductile Iron Durabar®, not pre-castings, so they could accurately be called Billet Ductile Iron! In addition to our ductile iron Big Jugs™ for Evos, we also offer ductile iron jugs for Knuckleheads, Pans, and Shovels (uses base studs and head bolts) featuring machined fins, stock oiling plus 3 times the strength of original cylinders. Big Jugs™ can be ordered as complete kits with Hytech™ pistons, rings, teflon buttons, Viton O-ring head gaskets, and high tensile strength studs, bolts, and nuts.