Zipper’s Stage IV ProMax CNC 2.0” Heads

Our High Output 2.0”Twin Cam© heads are designed for larger displacement, 4 inch+ bore engines. Both ports feature more extensive CNC porting and the intake valve seat is changed and valve size is increased to 2.0 inch. The combustion chamber is enlarged to 97cc and un-shrouded for increased intake flow. Stainless steel valves, Step-Lock guides, Viton® seals and high lift valve springs are installed after the seatwork is finished on our Serdi equipment. These heads are also machined for and include compression releases (on non-ACR equipped heads). Used on our 4.125″ bore Muscle 107”, 117”, 120” and 124” engine kits. This is the finest modified Twin Cam© head you’re likely to find anywhere!

Components Include:

• Full CNC Port and Combustion Chamber Machining
• Ductile Iron Step-Lock Valve Guides
• Competition Seat Work on Serdi Equipment
• 2.000” Int, 1.625” Exh Stainless Steel Valves
• Performance Valve Springs with Moly Collars
• Moly Valve Collars and Viton Valve Seals
• .750” Valve Spring Free Travel
• Manual Compression Releases Installed (if non-ACR heads)
• 97cc Combustion Chamber (Skim Decked)
• Completely Assembled, Ready To install

This service requires the heads from your motorcycle. We keep exchange heads in stock already modified for super quick turnaround. Parts must be in nearly perfect cosmetic condition (box heads individually with lots of newspaper or foam padding!); expect the same from us. Heads that are extremely dirty, stained, etched or have corroded finishes or damaged fins will be processed (10 working days) and returned to you. Remove heads from engine, wash off oil and ship to Zipper’s as-is. Because improper cleaning methods can actually do more harm than good, we suggest you allow us to properly prepare your parts for modification. Extreme care is taken during our preparation process to preserve component finishes. A small cleaning charge applies to exchange heads. Previously modified heads are not eligible for exchange.

*To ensure you enjoy a premium experience, Please fill out a Build Sheet/Job Order Sheet prior to completing an order on the website.
Click here for Zipper’s Build Sheet/Job Order Sheet

Not legal for sale or use in California on any pollution controlled motor vehicle.
Not legal for sale or use on any EPA pollution controlled motor vehicle.