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Screamin' Eagle Milwaukee-Eight Engine Stage IV Kit - 107CI to 128CI

$3,974.95
4.50
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See 4 reviews
Part Number: 92500078
Color: Black Highlighted
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This Stage IV Kit was designed to deliver maximum horsepower – all the way to the redline. Features new CNC-ported heads with 1mm bigger valves and fully machined combustion chambers. Coupled with the kit's high-lift SE8-517 cam, high compression pistons and a 64mm throttle body and intake manifold, this combination delivers a thrilling 126 ft-lb of torque and 121 HP rear-wheel output when paired with Screamin' Eagle Street Cannon Mufflers. It’s designed to run wide open at high-end RPMs and provide a significant boost of torque from cruising speed. You’ll feel the difference as soon as you twist the throttle. When installed by an authorized Harley-Davidson Dealer within 60 days of the vehicle purchase, compliant kits do not impact the vehicle’s limited warranty. Kit includes: CNC Ported Cylinder Heads with CNC machined chamber and 1mm larger valves L93, Stage IV Timer Cover, SE8-517 High-Lift Cam, Forged High Compression Pistons, High Performance Cam Bearing, Tappets, 4.31" Steel Sleeve Cylinders, 64mm Throttle Body and Cast Manifold and High Flow Injectors (5.5 g/sec).

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Reviews
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  • FEATURED REVIEW
    8/2/2020
    2017 SGS w/ 128 Big Bore Stage Kit
    Featured H-D Dealership H-D Employee Sweepstakes Entry Verified Purchaser Top 10 Contributor Top 25 Contributor Top 50 Contributor Top 100 Contributor Top 250 Contributor
    Want to 1st start off by saying I use all Harley parts to keep my warranty and extended service plan. After riding with a Stage 2 performance cam for a while, I pulled the trigger to have this installed. Using HD Pro Street Tuner and Smart Auto Tuner. After the break-in of 500 miles/2,500 rpms, I finally was able to start getting into the throttle and this is a torque beast!! It is manageable to ride around town in normal riding conditions but once you get into the throttle and the engine hits 3,500 rpms, hold on! Takes off like a rocket. I have learned to hold onto the left grip tightly before I throttle on. After I rode for 1,700 miles of all types of riding conditions, I went back to have the data from the Smart Auto Tuner downloaded into the ECM and what a difference it made!!! This is a lot of power to respect. Both the 128 and 131 have very close hp/torque numbers that you can’t tell the difference. You want to pass a semi on the highway, no problem. You want to pass a car, no problem. Keep your distance from any other vehicle/motorcycle in front of you because a twist of the throttle and you will be on them before you know it. I ride in the very back in group riding now because I can keep a further distance. If I lead, I tend to leave the group behind without realizing it. After purchase of the bike and riding for 10,000 miles, I did a Stage 2 performance cam. After 30,000 miles, I upgraded to the 128 kit and riding the motorcycle for these distances between factory and upgrades, you will notice you will have to ride the motorcycle different than before previous. With the 128 kit, you are running a lot of torque and thus have to adjust going into different types of corners but coming out and giving it throttle is a blast. You can be 20 miles above the posted speed limit before you know it so take that into account when adjusting riding style. Gas mileage is similar to factory if riding normal up to 55mph. Running interstate speeds of 65 burns a bit more and getting into the throttle will burn up gas but IT’S WORTH IT!!!! Only con is when running interstate speeds and getting into the throttle, the catalytic converter gets really hot. Your passenger WILL NOT LIKE IT. I might go with a Screaming Eagle header pipe where the converter is in the mufflers if riding 2 up a lot. There are those who will say “this or that” company makes better “this or that” parts better but I don’t wrench, don’t care too read more.
    TMurphy427 - Maryville, TN - Motorcycle: 2017 SGS
    • Update: Put 25,000 miles on it so far. From east coast to west coast. From beaches to tallest mountains in the Rockies and Cascades. From 35 degrees to 110 degrees. Been a solid motor. Switched out factory header for Fullsac MX after warranty expired.
      TMurphy427 - Maryville, TN
      1/26/2024
    • Delete the catalytic conver. Unless you're in California. They're starting to crack down on motorcycle emissions. I drilled out the convertor on my stage 1 2020 roadglide. Performance is the same. But less heat and a deeper exhaust tone.
      Oklahoma
      6/21/2023
    • Providing an update. After 15,000 miles with Stage 4 and traveling in all types of weather from the Mtns to the beach. Still performing great! After first review, I couldn't take it anymore with the exhaust and went with the Fullsac MX.
      TMurphy427 - Maryville, TN
      5/9/2022
    • I would take a piece of that action Beefy. Am familiar with the Fuel Moto kits and they are great....but...I just put the 131 Stage IV kit into my Softail, a 2018 FXBRS with V
      Soseeopath - Western USA
      3/18/2021
    • Beefy- Clearly TMurphy427 is looking to stay within his warranty and perhaps he has Screaming Eagle Performance extended warranty coverage. Yes, the FM engines outperform HD, but his reasoning makes sense to get more power under HD .
      Adam L - Bryant, AR
      2/16/2021
    • And how did that Fuel Moto bagger do in the MotoAmerica Bagger race??? Didn't see them there. And How did the all Harley 131 engine in the V
      TMurphy427 - Maryville, TN
      12/31/2020
    • hahahaha u left the stock head pipe on with a big bore kit?drinking the dealers kool aid like a lot of people. My 18 was built by fuel Moto and will blow any cvo or 131 off the road . 141.6HP to the wheel. for almost what you paid for SE parts
      Beefy - Ohio
      9/20/2020
  • FEATURED REVIEW
    5/24/2020
    SE 107 to 128 Kit 1st Impressions
    Featured H-D Dealership H-D Employee Sweepstakes Entry Verified Purchaser Top 10 Contributor Top 25 Contributor Top 50 Contributor Top 100 Contributor Top 250 Contributor
    My SE 107 to 128 kit installation is complete. First let me state that I only went with this kit over Fuel Moto because I had a boatload of Harley Visa reward points. My 1st run was with my SVT Boneshakers exhaust w/RCX 2-1-2 headers. I am using a Power Vision map with Target Tune that Jaime had sent to me. Bike seemed to stumble between 1900-2100, so I added more fuel and it seemed to run better. I ran it for about 5 miles around my neighborhood and it still seemed like it was struggling in the lower rpms. Jaime warned me that this might occur with the SVT Boneshakers due to the lack of restriction. Thankfully I had a brand new set of S&S GNX pipes in my garage, Jamie suggested these. After installing the S&S pipes it ran much better, but it is in need of dynotune and different cam. The SE8 517 cam that is included with the kit is nothing to brag about. As soon as I break her in a bit more I'll bring her to JD Cycles for a Dynotune. So do I notice a difference in power? Of course I do, I just think that there's still more to get of of that engine and a cam & dyno should get it. read more.
    • User review image
    tviscomi - Bucks County, PA - Motorcycle: Road Glide Special
    • Look up a S
      Oklahoma
      6/21/2023
    • What is the rev. limit with a factory warranty 128 kit install
      Harley Don - Indy
      7/25/2020
  • FEATURED REVIEW
    5/20/2020
    No Regrets
    Featured H-D Dealership H-D Employee Sweepstakes Entry Verified Purchaser Top 10 Contributor Top 25 Contributor Top 50 Contributor Top 100 Contributor Top 250 Contributor
    I was hesitant about this upgrade but what a difference. It reminds me of going from a six cylinder to an 8 cylinder engine. This upgrade definitely handles the weight of the bike and "me" much better than the 107 did. The only downside was there is a bit more vibration but is very tolerable.
    fireaway - Minnesota - Motorcycle: Street Glide Special
    • Vance
      Fireaway - Minnesota
      6/4/2020
    • What exhaust(s) are you running with your Stage IV kit? Also did you have it dynotuned?
      tviscomi - Phila
      5/20/2020
  • FEATURED REVIEW
    2/8/2020
    Well worth the upgrade
    Featured H-D Dealership H-D Employee Sweepstakes Entry Verified Purchaser Top 10 Contributor Top 25 Contributor Top 50 Contributor Top 100 Contributor Top 250 Contributor
    Well worth the upgrade. Had the 128 kit installed on my new 2020 Road King. Tourqe and pull throughout all ranges, loves to rev. Makes an 800lb bagger feel 300lbs lighter. Engine has a great lope to it at idle. Exhaust sounds good but not great as Street Cannon slip-on are the only "warranty compliant" option. Dealer could not get the Smart Tune module to fit due to clearance issues, but in my experience they don't make a huge difference for every day riding anyways. Overall a great kit. read more.
    • User review image
    • User review image
    Mrad84 - Alabama - Motorcycle: 2020 Road King
    • Keep barking about Fuel Moto! Their dyno numbers never stand up on any other dyno! Especially Harley Dealers! If you work for them I can speak first hand! Two of their kits one twin cam and one M8 came to Back missing 8-10 horsepower and Torque
      Roadking58 - Milwaukee
      12/6/2020
    • Have it actually tuned call fuel moto. Dealers are a joke they just download a map from a website them clowns don’t know how to tune anything and just charge you for the 3 hrs “dyno time”
      Beef - Ohio
      9/20/2020
    • My 2017 FLHRXS only has the 117" kit from the stock 107" with S
      Adrian - abbotsford.bc, canada
      6/9/2020
    • I have a 2020 Road Glide, and have the Rine Hart slip ons, will the slip ons fit with this upgrade?
      Whiplash - Arizona
      4/5/2020
    • That stage kit on a Road King without the weight of a fairing. It's got to be a beast!!! Looking at the numbers compare to a 131, it's very, very close to not know the difference. So if you are at stock 107 or 114, these stage kits will be very similar. Overlay the graph to the previous stage 4 kits and holy smokes what a difference.
      read more.
      TMurphy427 - Maryville, Tennessee
      2/28/2020
    • 124HP/134TQ With the canned map the dealer used.
      Mrad84
      2/16/2020
    • What kind of horsepower are you putting down?
      18 StreetGlide - Halifax, PA
      2/9/2020
Showing 1-5 of 29
Q&A
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  • Question:
    1/28/2025
    I also have a question, I have a breakout 117 2024 and I want to know if the engine can be replaced with the Screamin’ Eagle 135 Stage IV thank you
    Julian - Romania
    • Answer:
      Hi Julian: Please acontact your local dealership for further assistance. Thanks
      princessv
      Helpful?
  • Question:
    1/8/2024
    Are the SE Upgraded Valve Springs installed on these heads?
    • Answer:
      Hello Elijah, Please contact your local HD Dealership as this is a installation/technical question. thanks
  • Question:
    12/9/2023
    Is there a cat on the head pipe that comes with the Stages??
    Dudley - Nashville
    • Answer:
      Yes, there is a CAT that comes with the header. Run it if you want to have it covered under warranty. It gets too hot and I switched to the FULLSAC MX header pipe for more performance and the factory heat shields will fit using it. Highly recommend.
      TMurphy427
      Helpful?
  • Question:
    8/22/2023
    18 FLHXS ST GLD SP, I see that the 17-18 models need oil pump and clutch upgrade for 128. Will the flywheel last for longevity with this kit and any other parts needed to keep this build running and last?
    Kev15 - Oklahoma
    • Answer:
      I have a 124 SS kit on my 2023 CR482 cam.. the one that’s for 124/128 with high compression (11.5:1-12). I’m at 11.7:1. 130/140tq She boogies But I wonder how long it’ll be til I need to send the crank in for true/plug/weld to A1 or get an SS crank
      • Answer:
        The HD mechanics who did mine strongly suggested to use the upgraded SE oil pump
        TMurphy427
        Helpful?
  • Question:
    5/27/2023
    Will the stock clutch be able to handle the 128? Will the factory oil pump be able to quench the 128 Beast? I own a 2021 Road King Standard, I currently have the 107 Stage 2 Kit
    Brian J - NH
    • Answer:
      I have had this 128 kit on my 22 Road Glide for about a year now. The only issue I have encountered in 5k miles is that my 2 Brothers shorty exhaust is ungodly hot. Everything else, no issues, and I drive hard.

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Screamin' Eagle Milwaukee-Eight Engine Stage IV Kit - 107CI to 128CI