Most Potent Steet-Legal Harley Crate Motor Ever
The Screamin’ Eagle 135ci Stage IV Performance engine packs 130 horsepower and a whopping 143 lb-ft of torque.
If you’re familiar with Harley-Davidson’s touring bikes, you know there’s no shortage of ways to give them more power. But if you’ve looking for a plug-and-play solution that’ll give your Road King, Street Glide, or Ultra Limited a big shot of adrenaline, the MoCo has you covered. The new Screamin’ Eagle 135ci Stage IV Performance crate motor is compatible with touring models from 2021 and up, and with 130 horsepower and 143 lb-ft of torque on tap, it’s a monster of the mill.
Plus, since those figures were measured at the wheel, not the crank, you’ll see every pony you paid for on the dyno — and you’ll certainly feel it when you crack the throttle. The new engine was developed with the wizards from Harley’s Screamin’ Eagle factory racing team, and after they punched the displacement up to 135 cubic inches, they added a host of other go-fast bits.
Designed to thrive at wide-open throttle, the Stage IV is packing CNC-ported cylinder heads, a high-lift cam, and high-compression forged pistons, along with 68mm throttle bodies, a CNC-machined 68mm intake manifold, and fat 6.2 g/sec fuel injectors. To ensure consistent oil pressure, a billet Screamin’ Eagle Pro cam plate and oil pump are also along for the ride. Both Oil-Cooled and Twin-Cooled versions will be available, and neither engine requires any change to the mounts.
Of course, since this is the heart of a Harley, it’ll look as good as it performs. The engine will be available in either black or chrome, and each will sport distinct 135 Stage IV badging on the timing cover and the heads. It will also come with a two-year warranty, and as long as it’s installed at an official Harley-Davidson dealership, within 60 days of purchasing the bike. As you might expect, California-based riders are out of luck, because California, and trike owners also won’t be able to make the upgrade either.
Now, you might be thinking that all this additional power won’t exactly come cheap — and you’d be right. Before the cost of installation, you’ll have to shell out $7999.95 for the Screamin’ Eagle 135ci Stage IV Performance, so as mods go, it’s definitely big-ticket. That’s a lot to drop on an engine swap for a bike that’s — at the very maximum — two years old, but since there’s no mention of a core charge on Harley’s website, you’ll presumably get to keep your old engine, which is a big bonus. If this were me? After I had the techs drop in the Stage IV, I’d clean up my old mill and put it on display.
Photos: Harley-Davidson
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