Step 4: S&S CNC Ported Cylinder Heads and Fuel System Upgrades
Gain Up to 40 hp Over Stock!*
Step 4 of the S&S® 4-Step Performance Program is for the serious performance enthusiast. Most riders will have satisfied their craving for power in the first three steps, but if you are one of those who wants even more, here's Step 4. The results are very fast.
Upgrade Your Heads with CNC Porting
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 air flow while maintaining port velocity.
* Horsepower gains require components in previous steps.
Don't let your stock carb or EFI throttle body limit your horsepower! Give your CNC ported heads all the air they want with an S&S performance carburetor or throttle body. Carburetors depend on air velocity to deliver fuel, so while you want something bigger, too large a carb will hurt low rpm response. We generally recommend the 17/8" S&S Super E Carb for 97" engines. However, on the drag strip, the 21/16" S&S Super G carb will deliver the best top end horsepower. Since electronic fuel injection systems use a highpressure fuel pump and a computer to deliver fuel, velocity in the throttle body is not as critical. A larger throttle body will not degrade low rpm performance, so S&S recommends a 58mm throttle body for both 97" and 106" engines.