Intro
As a Harley Davidson owner or enthusiast and someone even mildly interested in a custom motorcycle there’s no doubt you’ve heard about the Stage I, II, III, & IV kits provided by Screamin’ Eagle. What do these “levels” of performance mean. What is involved? What are the implications with warranty? Do I need to get it done at a Harley Davidson dealership? What kind of numbers do these kits turn and how long will your bike be down for service? What will your bike sound and feel like once you get one of these kits installed? Let’s take a deep dive into the 4 levels of performance that these Screamin’ Eagle kits deliver.
Overview
Who doesn’t want a custom motorcycle or to add some cajun seasoning to your life?! With these custom motorcycle performance stage kits from Screamin’ Eagle you will notice a more responsive powertrain from your motorcycle engine. Who doesn’t love the classic Harley Davidson rumble that we are so used to? Harley Davidson hears you and they have provided a powerful lineup of stage kits through the Screamin’ Eagle performance platform for sounds and more importantly performence. These Screamin’ Eagle kits take the guess work out of putting together powerful and reliable motor configurations that are sure to push you back into the seat.
Harley Davidson engineers have spent a lot of time and money on the r&d for these products and are sure to work perfectly when built on the stock Harley Davidson Milwaukee 8 platform. You will witness improvements in horsepower, torque, and increased sound all while keeping your pocket book safe by allowing your motorcycle to stay under the Harley Davidson factory warranty if installed at a Harley Davidson dealership. Pretty good deal eh? Let’s dive in from least involved to most involved and from there you can decide what’s best for you.
Stage I: Intake and Exhaust
The entry kit for riders that want to add just a dash of Cajun Seasoning to increase sound and slightly enhance the performance of their Harley Davidson motorcycles is the stage 1 kit. The stock salt and pepper just doesn’t cut it. This kit includes a Screamin’ Eagle Stage 1 air breather, Screamin’ Eagle exhaust, and tuning to accommodate the increased air flow.
The stage 1 kit will be the most inexpensive step to take and is the building block in which all of the other kits build off of. Every subsequent kit has a stage 1 kit built into it. This is due to the fact that to increase power you have to increase airflow in (air cleaner) and out of (exhaust) the engine.
This kit alone will increase your horsepower and torque by up to 10%. The price will vary depending on the air cleaner and exhaust options you go with. Visit your local Harley Davidson dealership for more details on your specific application. For more detailed information on each aspect of this kit and how it works with other kits check out the video below.
Stage II: Stage I + Cam Uprgrade
This kit is bundled on top of the Stage 1 platform and simply adds a higher lift and duration cam along with adjustable push rods to the recipe. A slightly larger dash of Cajun Seasoning, if you please. This upgrade is all about increasing the torque and/or horsepower of the engine without increasing the available displacement.
Cams do two things inside the engine. They increase the lift of the valves meaning the valves open to a greater degree than stock. They also increase the duration of the lift meaning while the valve is open to a greater degree it is also left open for a longer period of time.
Choosing a cam depends on your particular riding style. Cam styles fall under two main categories.
1. Power 462 Cam: Created for the light to light riders who want power all the way through to redline. More for drag racing style of riding over cruising.
2. Torque 447 Cam: Perfect for riders who want the best power at cruising speeds.
With the Power cam the rider will feel up to a 30% increase in horsepower and 10% increase in torque in the mid to upper rpm range. The rider has to keep the engine rotating at a high rate to feel the power.
The Torque cam on the other hand will get you up to a 15% increase in power in the low to mid rpm range instead of in the mid to high rpm range like the power cam. So at cruising speed, in low rpms you simply twist the throttle and the bike delivers exceptional performance via the cam without having to downshift to reach higher rpms.
Check out this video below for more detailed information. As always contact your local Harley Davidson dealership for more details about installation.
Stage III: Stage I + Big Bore Cylinders, Pistons, and Cam
Now we’re getting spicy! Designed for riders who want even more power delivered through increased engine displacement. This increases the power throughout the entire RPM range. A whole kaboom of Cajun Seasoning in this one.
This kit comes with either 128CI or a 131CI cylinders with a a domed high compression piston and a 498 cam. This cam is even more radical than the two cam options in the stage 2 kit. This is why the stage 3 doesn’t include a stage II. It bypasses that stage by going bigger all around.
The performance increase is about 35% in the mid to upper RPM range while maintaining plenty of roll on throttle for passing up cars at highway speeds. It will also make that distinct Harley rumble even more noticeable due to the increase in air flow of the engine.
Check out this video below for more detailed information. As always contact your local Harley Davidson dealership for more details about installation.
Stage IV: Stage III + Heads, Throttle Body, Cam, Lifters, and High Performance Clutch Components
Bruh, you better watch out. The lid on the Cajun Seasoning done came unscrewed. No worries just mix dat in. Built for the riders who want the best overall performance available without voiding Harley Davidson’s factory warranty if installed at a Harley Davidson dealership. Yum yum come get you some.
This kit has everything that the Stage III has to offer but addresses the top end of the engine as well as other modifications to make the transition to this much power that much more seamless. A Stage IV provides CNC ported cylinder heads and larger bore 64mm throttle body. With this setup the Milwaukee-Eight requires and even more radical cam than the stage II and stage III kits, the 518 cam. This top end and cam setup will increases the volume and velocity of air and fuel into the engine. This will then maximize the available power on a larger displacement Harley Davidson Milwaukee-Eight engine.
To harness all of that power Harley Davidson also includes some clutch components and high performance lifters. That way your engine stays bulletproof even with the increase in power.
The increase in power is about 25% increase in torque but an up to 50% increase in horsepower in mid to high range rpms! You get a race bike that is not only street legal but remains under the Harley Davidson factory warranty if installed at a Harley Davidson dealership. You won’t be able to find a deal like this anywhere else.
Check out this video below for more detailed information. As always contact Cajun Harley Davidson for more details about installation.
Screamin’ Eagle 131 Milwaukee-Eight Crate Engine
Built in Milwaukee from the ground up, the 131 is the baddest and largest engine from the Harley Davidson factory that can be dropped inside of a stock Harley Davidson bike. Built for the guys that want the best and spiciest there is to offer. No special frame fabrication or engine mount relocations are required. It also allows you to keep factory warranty if installed at a Harley Davidson dealership.
Check out this video below for more detailed information. As always contact your local Harley Davidson dealership for more details about installation.
Tuning
Any one of these Screamin’ Eagle kit upgrades will require an ECM (engine control module) recalibration to account for the different volumes of fuel and air required to allow your engine to perform like it should. This recalibration is known as tuning. The best method, and the method that will allow you to keep your factory warranty if installed at a Harley Davidson dealership, is the Screamin’ Eagle Pro Street Tuner and Smart Tune Pro.
The Screamin’ Eagle Pro Street Tuner offers base calibrations for your chosen Screamin’ Eagle stage kit. It will then constantly monitor the engine operation. Manual adjustments can be enabled to fine tune certain parameters within certain throttle ranges. A fine tune is perfect for specific applications and purpose built engines.
You can piggy back the Pro Street Tuner with the Smart Tune Pro that offers an auto tuning feature. This feature will automatically make adjustments throughout the entire RPM range while the bike is being ridden. This offers a big advantage if you have a touring model Harley Davidson and are going to be riding cross country in various altitudes and conditions. The Smart Tune will make adjustments as conditions change to keep your Milwaukee-Eight chugging along nicely.
Of course there are tons of after market options out there , but buyer beware. Most of these companies don’t have the capital or resources to invest into the R&D of these tuning methods like Harley Davidson does. They will also void your warranty. Harley Davison electronics are smart and can detect if any tuner other than a Harley Davidson tuner has been installed, even if no trace of the tuner remains on the bike.The VIN will be flagged in Harley Davidson’s system and any power train warranty claims will likely be denied.
Have fun and safe riding!