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Random freezes, missing sound and display glitches usually trace back to one bad driver. Find and replace yours safely.Free scan · under a minuteHarley-Davidson’s air/oil-cooled Screamin’ Eagle 135 Stage IV crate engine stands out for its claimed output: 144 horsepower and 149 lb-ft of rear-wheel torque. Those are manufacturer figures for U.S. part 16200978, not independent dynamometer results. Its appeal comes with important qualifiers: fitment is restricted by model and year, some installations need additional parts and tuning, and emissions eligibility varies by location.
What makes the 135 Stage IV notable?
Harley-Davidson describes the 135 as the most displacement and power it has created for a street-compliant crate performance engine. That is the company’s promotional positioning, not an independently verified ranking across the market. The engine’s 135-cubic-inch size and advertised rear-wheel output nevertheless make it a significant factory performance option for eligible Touring motorcycles.
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Screamin' Eagle 41000008C Pro Street Tuner for Harley Davidson | $624.99 | Buy on Amazon |
For the air/oil-cooled U.S. version, part 16200978, Harley-Davidson currently claims 144 horsepower and 149 lb-ft of rear-wheel torque. No independent dyno result is established here, so treat those numbers as the manufacturer’s claims rather than a guaranteed result on every motorcycle. Harley-Davidson lists the engine at $8,349.95; check the live listing or a dealer for current pricing and availability. Harley-Davidson’s product listing
What is included, and what do the specifications say?
Harley-Davidson lists these major components in the crate engine:
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- Extreme CNC-ported cylinder heads and an SE8-550 high-lift cam
- High-compression forged pistons and 4.31-inch steel-sleeve cylinders
- A 68mm throttle body with an Extreme Flow intake manifold
- High-performance cam bearing and tappets
- A 4 5/8-inch flywheel and 6.8 g/sec fuel injectors
- A Screamin’ Eagle Pro Billet Cam Plate and Oil Pump
The current product page lists an 11.6:1 compression ratio. Harley-Davidson service information for a documented 135 crate engine gives 135.3 cubic inches (2,217 cc), a 4.310-inch bore, a 4.625-inch stroke, and a 10.7:1 compression ratio. Because those official sources disagree on compression, the 10.7:1 figure should not be assumed to describe the current part 16200978 or the same revision. Harley-Davidson Service Information
Which motorcycles does the air/oil-cooled version fit?
The current U.S. listing gives this fitment for part 16200978:
- 2023-later FLHXSE and FLTRXSE
- 2024-later FLHX, FLTRX, and FLTRXSTSE
- 2026-later Touring models
Harley-Davidson says 2023–2024 models require a separately purchased cylinder-head retrofit kit, part 29900147. The listing also says the engine does not fit California models. Confirm the exact motorcycle’s model, year, cooling system, and market eligibility with Harley-Davidson or an authorized dealer before ordering. The current part listing is the better guide to present fitment than the broader launch-era description.
When Harley-Davidson announced the engine on March 1, 2023, it described it as intended for bolt-in installation in a 2021-later Touring chassis. That launch announcement predates the detailed fitment now shown for part 16200978, so it should not be read as a current guarantee that every 2021-or-newer Touring motorcycle is compatible. Harley-Davidson Media Site
What else is needed for installation?
The engine is not necessarily a complete, ready-to-run installation by itself. Harley-Davidson identifies a head pipe, part 65600177, as a separate purchase and requires ECM recalibration with a Pro Street Tuner. The company recommends dealer installation.
- Verify fitment: Have a dealer confirm the exact model year, configuration, cooling system, and local-market eligibility.
- Confirm the additional parts: For applicable 2023–2024 motorcycles, account for the separately purchased cylinder-head retrofit kit, part 29900147. The head pipe, part 65600177, is also sold separately.
- Plan for calibration: Arrange ECM recalibration with a Pro Street Tuner as specified by Harley-Davidson.
- Check the applicable requirements: Confirm emissions equipment and warranty terms for the motorcycle and location before installation.
How is the Twin-Cooled 135 different?
Harley-Davidson also lists a separate Twin-Cooled 135 Stage IV crate engine, part 16200787. It is not the same configuration as the air/oil-cooled part 16200978, and its fitment restrictions differ, including the exclusion of some later center-cooled Touring models. Harley-Davidson lists 143 lb-ft of rear-wheel torque for the Twin-Cooled version. Do not use that figure or its fitment rules for the air/oil-cooled engine; check the listing for the specific part and motorcycle. Harley-Davidson’s Twin-Cooled listing
What do the emissions and warranty notes mean?
The U.S. listing says the air/oil-cooled engine is 49-state U.S. EPA compliant, is not available for sale or street legal in all countries, and excludes California models. It also warns that a replacement engine must retain emissions devices appropriate to the vehicle and model year. These are manufacturer statements, not a universal determination of legality for every jurisdiction or modified motorcycle; check local rules and the dealer’s guidance for the specific bike. Harley-Davidson reports a one-year limited warranty. Review the current warranty terms with the company or an authorized dealer before purchase.
Is the 135 Stage IV the right choice?
It is most relevant to owners of a listed Touring model who want a high-output crate-engine option and can meet the associated fitment, parts, tuning, and emissions requirements. The advertised 144 hp and 149 lb-ft are compelling headline figures, but they remain manufacturer claims; the product page does not establish what a particular motorcycle will produce after installation. Start with exact fitment and total installation requirements, then compare the price and warranty terms against the performance goal.
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Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
