Harley Stage 4 UpgradeThe more air your engine can move, the more power it can create. With all other performance stages completed, there is one last upgrade that can help increase your mill’s ability to move air. That is the Stage 4 upgrade. The Harley Stage 4 upgrade consists of ported heads and a high performance carburetor or throttle body. These upgraded components will maximize the amount of fuel that your V-Twin can burn, which in turn, increases its ability to create more power.
Ported heads can dramatically increase the amount of air flow. The machined intake and exhaust ports maximize the amount of air that is able to enter and leave the combustion chamber. The process of exhaust scavenging is also increased with ported heads. Porting the heads also reduces the amount of turbulence the air stream encounters. Less turbulence in the air stream allows a consistent flow in and out of the engine for consistent performance.
With the ability to flow more air with ported heads, you have to get it there. A performance carburetor or throttle body is how you accomplish that task. Aftermarket performance carbs and throttle bodies are able to move a greater volume of air/fuel to the cylinder heads. Although you will want to choose a larger carb, you may not want to get the biggest. Too large of a carb can hinder your low end performance. Throttle bodies are bit different because they are computer controlled.
For those looking to finish their Harley’s engine overhaul, a Stage 4 upgrade has to be implemented. And for the riders who chose to go this far will be rewarded with massive performance gains. At Dennis Kirk, you will be able to find everything you need to finish a Stage 4, whether it’s aftermarket heads, carburetors or throttle bodies. Use the Ride Selector at the top of the page to find all of the parts that fit your specific motorcycle. Also, feel free to contact our knowledgeable Tech Team if you have any questions on which parts are best for you and your Harley.