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CNC Ported Cylinder Heads

Let S&S CNC Port Your Heads

CNC heads

Send your stock heads to S&S and we’ll use our state of the art CNC machining centers to reshape both intake and exhaust ports, as well as the combustion chamber. The goal is to maximize airflow while maintaining port velocity. Gain horsepower without losing low-end torque. More air more power. It’s pretty simple. It’s true of stock engines, and if you’ve increased your displacement, your larger engine needs even more air to make sure it lives up to its potential. Let S&S CNC port your stock cylinder heads to improve the flow and provide the air your engine needs. When your S&S dealer sends your heads to S&S, rest assured you will get your own heads back, but with vastly improved ports and combustion chamber. You have the option of several combustion chamber volumes, and either .585" or .650" capable valve springs so you can install higher lift cams for even more power! Don’t have a set of heads to send us? Stock heads with S&S CNC porting are also available for outright sale.

Features and Benefits

  • CNC machined ports are consistent - repeatable performance increase
  • High flow and high port velocity - great power without losing low RPM torque
  • Assembled with performance valves and your choice of .585" or .650" lift springs ready to bolt-on
  • Stock heads with S&S CNC porting are also available for outright sale in select models

Big Twin CNC


  • Fits 1999-up big twin engines
  • Ideal for 88" - 124" engines to make the most of your big bore kit!
  • Combustion chambers are available in the following volumes:
    • 83cc - For higher compression than stock
    • 85cc - For stock compression
    • 87cc - Recommended for up to 117" engines
    • 90cc - For large displacement big twins 124" and up

cnc-heads-xl-dyno.JPGXL CNC

  • Fits 2004-Up XL with 883 cc and 1200cc or greater displacement
  • Combustion chamber volume of 60cc - For stock compression in 883cc and 1200cc engines

S&S CNC Porting Service

  • 1999-Up Big Twin Engines
    • CNC Porting Service - S&S Ports Your Heads. 
      • 106-5880
      • $950.00
    • CNC Ported Heads - Complete Set Sold Outright. 
      • 106-5880
      • $1,400.00

2004-Up XL

  • CNC Porting Service - S&S Ports Your Heads. 
    • 909-0011
    • $950.00
  • CNC Ported Heads - Complete Set Sold Outright. 
    • 909-0011
    • $1,400.00


S&S® CNC Porting Service - Specification Comparison

Heads Valve Size Max Valve Lift Max TDC Lift Port Flow Chamber Volume
Intake Exhaust Intake Exhaust Intake Exhaust
 Big Twin    Stock    1.805"    1.575"    .585"    –    –    216.2 cfm    191.8 cfm    85cc  
 CNC Ported by S&S    1.900"    1.610"    .650"    .230"    .215"    248.6 cfm    209.7 cfm    83cc, 85cc, 87cc, or 90cc  
XL  Stock    1.805    1.575    .585    –    –    218.2 cfm    186.7 cfm    60cc  
 CNC Ported by S&S    1.830    1.575    .650    .213    .215    249.3 cfm    206.0 cfm    60cc  

 *Flow testing performed on a SuperFlow® 1020 flow bench at 28" of water test pressure at .600" lift. ** As a general rule of thumb, for every 1cc decrease in chamber volume equals a .1 increase in compression ratio.


NOTES: For XL applications. S&S recommends for use with cam TDC lifts no greater than: .213" intake, .215" exhaust to achieve .050" valve to valve clearance.

CNC porting is not available for previously ported heads, heads that have been structurally damaged, or heads that are determined to be unserviceable during initial inspection. These
heads will be returned to the customer without modification. In these cases, the customer will be notified and options will be reviewed. As an alternative, S&S heads or CNC ported stock
heads are available for purchase.
Due to variations in stock cylinder head castings, all inside surfaces of the ports may not “clean up” during machining. As a result, the inside of one or more ports may not appear to be
completely machined. This does not effect performance and is not considered a defect.
CNC porting is not currently available for Harley-Davidson® CVO engines or Screamin’ Eagle® cylinder heads.
Not legal for sale or use on CA or EPA pollution controlled motorcycles.