CNC Porting Services for Harley Heads



Zipper's pioneered CNC-porting in Twin Cam® Harley heads in 1999 with the first TC Performance Kit. With 19 years of experience we have expanded our line of CNC ported and combustion chamber designs to cover most popular Screaming Eagle and aftermarket engine configurations for Harley engines.

Zipper's CNC Ported Twin Cam Harley Cylinder Heads
• Stage 1.8 CNC port fitted for 1.850 intake to use on engines with stock O.E. pistons with shallow valve pockets- 85cc
• Stage 2.0 High velocity ports with larger 7mm 1.900 valves designed for 103, 107 CI engines with aftermarket flat top pistons 85 cc
• Stage 3.0 Larger ports/ increased air flow, 1.900 full CNC chambers, ideal for higher output engines with dome pistons and larger Throttle Bodies, chambers 91cc
• Stage 3.5 Special high flow oversize ports machined into an O.E castings. Special O.S. seats, 2.00 Intake valves with 92 cc chamber
• Stage 4.0 The largest port we can machine into an O.E castings. 2.00 Intake valves for max flow with fully un-shrouded 98 cc chambers

CVO-MVA Castings
• Stage 2.5- Fully CNC ported designed specifically for engines using the Screaming Eagle 117 kit with flat top pistons. Head Uses CVO standard valve sizes to retain a 95cc chamber
• Stage 3.0- Currently our maximum flow head CVO castings, Excellent port design w/oversize intake/exhaust valves, ideal for max output engines-101 cc chamber. Minimum valve sizes are 2.100/1.650 or larger

Stated chambers volume is based off full deck, custom decking can be accomplished to reduce chamber volume for specific compression targets.

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