2016-2017 Harley-Davidson FLSTFBS Fat Boy S: Twin Cam 110B Softail

The 2016-2017 Harley-Davidson FLSTFBS Fat Boy S was the most muscular factory Fat Boy of the Twin Cam Softail era: a two-year, blacked-out production model built around the counterbalanced Screamin' Eagle Twin Cam 110B engine. It sat within the Harley-Davidson Fat Boy family, but it was not merely a paint-and-trim exercise. The Fat Boy S brought a 110 cubic-inch engine, ABS, cruise control and a darker factory-custom treatment to a chassis whose basic Softail silhouette still traced its lineage to the original 1990 FLSTF Fat Boy.

Its significance is partly mechanical and partly chronological. The FLSTFBS arrived near the end of the Twin Cam Softail generation, just before the 2018 Softail redesign and the arrival of Milwaukee-Eight Softails. For collectors and serious Harley buyers, that places it in a useful and increasingly distinct category: the last-era Twin Cam Fat Boy with the largest factory-displacement counterbalanced Twin Cam engine offered in the regular Softail line.

Best Known For: the FLSTFBS Fat Boy S is best known as the factory blacked-out, Twin Cam 110B-powered Fat Boy produced for 2016 and 2017, making it one of the final high-displacement Twin Cam Softails before the Milwaukee-Eight chassis reset.

Quick Facts

The following summary is aimed at identification and buyer research rather than brochure trivia. It focuses on the mechanical architecture and features that separate the Fat Boy S from standard Fat Boy models and from later Milwaukee-Eight machines.

The important phrase is Twin Cam 110B. In Harley-Davidson usage, the B suffix identifies the counterbalanced Twin Cam engine used in Softail applications. That matters because the Softail frame did not use rubber mounting in the same manner as contemporary Touring models; balance shafts were essential to making the rigid-mounted big Twin Cam acceptable in a production cruiser.

Why the 2016-2017 Fat Boy S Matters

The Fat Boy S deserves a separate page because it represents a very specific moment in Harley-Davidson product planning. By 2016, the Fat Boy name was already deeply embedded in popular Harley culture, but the original visual recipe had been stretched through fuel injection, wider rear tires, larger engines and increasingly darker factory-custom styling. The Fat Boy S was Harley-Davidson's answer to customers who wanted the familiar solid-wheel Fat Boy stance without having to build the traditional intake, exhaust, engine and black-trim package themselves.

Mechanically, the model moved the regular-production Fat Boy concept closer to the territory that had previously belonged to higher-spec Screamin' Eagle and CVO machinery. Harley-Davidson did not publish a standard horsepower figure for the model, but the company did list engine torque at 108 ft-lb at 3000 rpm in U.S. specifications, a meaningful increase over ordinary 103-powered Softails of the period. It was not a superbike and was never intended to be one. Its point was low-speed authority, visual weight and factory-backed big-inch character.

The historical reason it remains interesting is timing. The FLSTFBS was among the final expressions of the Twin Cam Softail Fat Boy before the 2018 platform changed the frame, suspension philosophy and engine family. To a collector, that makes it less a generic late-model used Harley and more a bookend: the big-displacement factory Twin Cam Fat Boy at the close of an era.

Historical Context and Development Background

When the Fat Boy S appeared for the 2016 model year, Harley-Davidson was operating in a cruiser market very different from the one that had greeted the first Fat Boy in 1990. The heavyweight American cruiser had become mature, highly accessorized and intensely image-conscious. Competitors from Indian and the Japanese manufacturers were offering large-displacement cruisers with strong torque and modern equipment, while Harley's own customers expected factory bikes to arrive closer to the finished custom look that earlier owners would have created through the accessory catalog.

The Softail line was central to that strategy. It gave Harley-Davidson the visual language of a rigid-frame custom while retaining rear suspension, and the Fat Boy was one of its most recognizable shapes: broad fork, substantial front end, wide tires, solid wheels and a low, muscular posture. The 2016 Fat Boy S took that vocabulary and removed much of the brightwork. Black engine finishes, dark wheels, blacked-out trim and a more aggressive stance aligned it with the factory dark-custom movement rather than the polished boulevard-cruiser idiom of earlier Fat Boys.

The use of the Twin Cam 110B was the decisive engineering move. Earlier regular Fat Boy models had used smaller Twin Cam displacements, including 88, 96 and 103 cubic-inch versions depending on model year and market. The 110 had long been associated with Harley-Davidson's performance accessory and premium factory programs, so placing a counterbalanced 110 in the Fat Boy S gave the model a sharper identity without altering the fundamental Fat Boy silhouette.

There was no racing or military mission behind the FLSTFBS. Its arena was the showroom, the open road, the dealer-custom culture and the owner who wanted a factory Softail with presence and torque rather than a blank canvas. In that respect, it is a useful study in late Twin Cam Harley-Davidson thinking: heritage appearance, enlarged displacement, electronic convenience and factory-applied custom finish.

Engine and Drivetrain

The heart of the FLSTFBS was Harley-Davidson's air-cooled Screamin' Eagle Twin Cam 110B. It was a 45-degree, pushrod-operated, overhead-valve V-twin with two camshafts and internal counterbalancers for Softail use. The 110 cubic-inch displacement corresponds to 1801 cc, with Harley-Davidson factory literature commonly listing a 4.000 in bore and 4.374 in stroke.

Fueling was by Electronic Sequential Port Fuel Injection. Ignition was electronic, and the engine retained the dry-sump lubrication architecture expected of modern Harley big twins. The clutch fed a six-speed Cruise Drive transmission through the primary drive, and final drive was by belt, consistent with contemporary Harley-Davidson heavyweight street machines.

Harley-Davidson generally emphasized torque rather than horsepower in its factory specifications, and that distinction matters for researchers. The Fat Boy S is commonly listed by Harley-Davidson with 108 ft-lb of torque at 3000 rpm in U.S. trim, while factory horsepower was not part of the regular published specification set. Aftermarket dyno figures vary with exhausts, calibrations and test conditions and should not be treated as factory numbers.

Engine and Drivetrain Specifications

This table contains mechanical figures and descriptions that are central to identifying the Fat Boy S powertrain. It deliberately omits non-factory dyno horsepower and performance claims.

The 110B's appeal is not subtle. It gives the Fat Boy S the heavy flywheel feel and off-idle authority expected of a large Harley V-twin, with the counterbalancers reducing the kind of rigid-mounted vibration that would otherwise dominate the experience. Modified examples are common, especially with aftermarket exhausts, high-flow air cleaners and engine calibrations, so buyers should distinguish a stock 110B motorcycle from one that has been tuned for more output.

Chassis, Suspension and Braking

The Fat Boy S used the pre-2018 Twin Cam Softail chassis, a steel frame architecture designed to hide the rear suspension beneath the motorcycle and preserve a hardtail-like profile. That visual trick was central to the Softail identity. On the Fat Boy S, the chassis was combined with wide tires, solid-disc wheel styling and a low, broad stance that made the motorcycle look heavier than many specification-sheet comparisons suggest.

At the front, a conventional telescopic fork carried the substantial Fat Boy front end and headlamp nacelle treatment. At the rear, horizontal hidden shocks worked beneath the frame. This layout did not give the feedback or bump absorption of the later 2018 Softail redesign, but it gave the FLSTFBS the exact silhouette many buyers wanted: low, long, visually rigid and unmistakably Fat Boy.

Braking was by hydraulic discs with ABS fitted as standard on the Fat Boy S. The factory wheel and tire package is another key point of identity, particularly the 140/75R17 front and 200/55R17 rear tire sizes commonly listed in Harley-Davidson specifications for the model.

Chassis and Equipment Specifications

The chassis table is useful for separating the FLSTFBS from earlier narrow-rear Fat Boys, 103-powered Softails and later Milwaukee-Eight Fat Boy models.

The numbers explain some of the road behavior. A 731 lb running-order motorcycle with a 200-section rear tire is not built to disappear beneath the rider. It asks for deliberate inputs, rewards a smooth throttle hand and carries its visual mass honestly.

Riding Experience and Mechanical Character

The Fat Boy S starts like a modern fuel-injected Harley, not like an old choke-and-petcock machine. Turn on the ignition, let the fuel system prime, thumb the starter and the 110B settles into the familiar big-twin cadence through its counterbalanced Softail mounting. There is no hand shift or foot clutch ritual here; the FLSTFBS uses contemporary hand clutch and foot shift controls, with the rider interface centered on low seat height, forward footboards and a wide bar.

The engine is the dominant feature. The 110B does not need revs to make its point, and the factory torque peak at 3000 rpm tells the story better than any unsupported horsepower claim. Throttle response is shaped by EFI and emissions-era calibration, but the underlying character is large-bore Harley: a heavy pulse, audible valvetrain and primary-drive presence, and a broad shove that suits short-shifting through the six-speed gearbox.

The clutch and gearbox are substantial rather than delicate. A well-maintained example should shift cleanly, but the rider is always aware of the mechanical scale involved: wide belt, large primary, big rotating assembly and a drivetrain built around torque rather than high-rpm urgency. Modified exhausts can make the motorcycle feel crisper or simply louder, depending on the quality of the calibration.

On the road, the chassis gives the expected Twin Cam Softail behavior. It is stable and planted at cruising speed, especially on open roads, but the wide rear tire and long, low layout make low-speed maneuvers more deliberate than on a lighter Dyna or Sportster. Braking is adequate for the mission when properly serviced, with ABS adding a useful safety margin, but the rider should never mistake the Fat Boy S for a modern sport-standard in stopping distance or corner-entry feedback.

The sensory appeal is inseparable from the look. The blacked-out engine, solid-wheel visual mass, headlamp nacelle and broad tires make the machine feel like a production custom even before it moves. That is exactly why many were bought: not to be the sharpest-handling Harley, but to deliver the last-generation Twin Cam Softail Fat Boy experience with factory big-inch authority.

Identification and Originality

The first identification point is the factory model code: FLSTFBS. It identifies the Fat Boy S within the Twin Cam Softail naming structure, and it should be supported by the motorcycle's documentation, frame VIN, service records and factory equipment. Avoid relying on trim alone. Many standard Fat Boys have been blacked out, fitted with Screamin' Eagle air cleaners or modified with large-displacement engine kits, and those motorcycles are not automatically FLSTFBS models.

Correct examples should show the defining Fat Boy S combination: Twin Cam 110B engine, blacked-out factory finish, Fat Boy solid-wheel visual identity, ABS, cruise control and the late Twin Cam Softail chassis. The engine cases should be examined for the proper factory markings and for evidence of replacement cases, major performance work or non-original finishes. On modern Harleys, the frame VIN and engine number relationship should be treated seriously; mismatches, salvage branding or undocumented case replacement can affect both value and insurability.

Paint and finish matter more than many casual buyers assume. The Fat Boy S was sold with a deliberately dark factory appearance, commonly associated with Vivid Black and Denim Black finishes. Repainted tins, powder-coated parts, non-factory chrome substitutions and incorrect wheels may not hurt a rider-grade machine, but they reduce the motorcycle's appeal as a documented two-year factory variant.

Common changes include exhaust systems, air cleaners, fuel tuners, seats, handlebars, turn signals, license-plate mounts and suspension alterations. None is unusual in the Harley world, but originality is easiest to defend when the owner has the stock exhaust, intake components, take-off trim, factory manuals, key fobs, service receipts and original sales paperwork. For a collector-grade Fat Boy S, those paper and parts trails are often the difference between a desirable preserved motorcycle and a modified cruiser with the right badge.

Model Code and Variant Breakdown

The FLSTFBS is often researched alongside other Fat Boy codes because the family name continued across several engines and chassis generations. The table below separates the specific Fat Boy S from the surrounding models most commonly confused with it.

There were no widely recognized police, military or racing versions of the FLSTFBS Fat Boy S. Its collectability rests on its short production window, engine specification and place in the final Twin Cam Softail period, not on institutional service or competition history.

Performance and Dimensional Specifications

For the FLSTFBS, the most reliable performance figure to cite is Harley-Davidson's factory torque listing: 108 ft-lb at 3000 rpm in U.S. specification. Harley-Davidson did not publish a regular factory horsepower rating for the model, and aftermarket dyno results should be treated as results for individual motorcycles rather than factory specifications.

Factory dimensional data commonly lists the Fat Boy S at 731 lb in running order, with a 5.0-gallon fuel capacity and the 17-inch tire combination noted above. Top speed, 0-60 mph and quarter-mile figures are not central factory identity figures for this model and vary too heavily with rider, condition, surface, exhaust, calibration and testing method to be useful as collector documentation.

In real-world terms, the motorcycle's performance is defined by immediate torque rather than terminal speed. A standard machine should feel strong from low rpm, relaxed in top gear and mechanically comfortable at highway pace. If it feels flat, overheated, noisy in the cam chest or poorly calibrated after exhaust changes, the issue is more likely maintenance or modification history than a lack of inherent engine capacity.

Compared With Related Harley-Davidson Models

Fat Boy S vs Standard Twin Cam Fat Boy

The standard Twin Cam Fat Boy shares the broad Softail identity and visual DNA, but the Fat Boy S is the more specialized machine. Its 110B engine, blacked-out finish, ABS and cruise control distinguish it from ordinary 103-powered Fat Boys of the same general period. For a buyer, the question is whether the larger engine and two-year S identity justify less flexibility in color, finish and originality.

Fat Boy S vs Fat Boy Lo / Fat Boy Special

The Fat Boy Lo and related dark-finish Fat Boy variants helped establish the lower, darker factory-custom direction that the Fat Boy S later intensified. They can look similar at a glance, especially after owner modifications. The engine is the decisive separator: a true FLSTFBS is a factory Twin Cam 110B motorcycle, not simply a dark Fat Boy with aftermarket parts.

Fat Boy S vs Low Rider S

The 2016-2017 Low Rider S is an important comparison because it also used a 110 engine and has become a strong enthusiast favorite. The Low Rider S, however, belongs to the Dyna platform rather than the Softail platform and has a different chassis feel, riding position and collector following. The Fat Boy S is the heavier, lower, more visually traditional Softail expression; the Low Rider S is generally the more handling-oriented factory performance cruiser of the pair.

Fat Boy S vs 2018-on Milwaukee-Eight Fat Boy

The 2018 redesign changed the Fat Boy more than a casual observer might expect. The Milwaukee-Eight Softail frame, revised rear suspension and new engine family made the later bike more modern in function. The FLSTFBS remains attractive to riders and collectors who specifically want the last Twin Cam Softail architecture, the 110B engine and the pre-2018 Fat Boy silhouette.

Restoration and Ownership Notes

Because the Fat Boy S is a modern Harley-Davidson, parts availability is generally far better than for genuinely antique motorcycles. Service parts, gaskets, belts, brake components, suspension pieces and many engine parts are supported by the Harley aftermarket as well as specialist shops. The challenge is not basic serviceability; it is separating careful upgrades from poorly executed customization.

The Twin Cam 110B should be evaluated with the seriousness appropriate to a large-displacement air-cooled engine. Heat management, oil quality, cam chest condition, lifter health, compensator wear and evidence of correct tuning after intake or exhaust changes all matter. A loud exhaust and a fuel tuner do not guarantee a healthy engine, and a stock-appearing motorcycle with complete records is often the safer long-term purchase.

Hydraulic cam-chain tensioner systems used in later Twin Cam engines are a substantial improvement over earlier spring-loaded arrangements, but cam chest inspection is still sensible on a high-mileage or modified 110. Lifters, pushrods, cam bearings and oil pump condition deserve attention during any major service. If the engine has been opened, documentation should identify who performed the work, what parts were used and whether the calibration was matched to the mechanical changes.

Originality is the other major ownership issue. Many Fat Boy S motorcycles were bought by owners who immediately changed pipes, bars, seats and air cleaners. That is normal, but for collector interest the ideal machine retains its factory identity and includes removed original parts. A motorcycle with missing stock exhausts, no tuner documentation, unknown cam work and cosmetic repainting may still be an excellent rider, but it should not be valued like a carefully documented original example.

Buyer and Restoration Inspection Points

The Fat Boy S is new enough that catastrophic corrosion and missing unobtainable parts are less common than on vintage motorcycles. The sharper inspection focus is modification quality, engine health, documentation and whether the motorcycle is truly an FLSTFBS rather than a dressed-up Fat Boy.

A clean Fat Boy S should feel cohesive: correct code, correct engine, consistent finish, believable mileage and a modification record that makes mechanical sense. Walk away from motorcycles whose paperwork is vague, whose engine work is undocumented or whose seller cannot explain the tuning after intake and exhaust changes.

Collector and Market Relevance

The FLSTFBS is not rare in the sense of a prewar Harley, a factory racer or a limited-production homologation motorcycle. Its appeal is different: it is a short-run, late Twin Cam Softail variant with the factory 110B engine and a clearly defined visual package. Those are exactly the attributes that tend to matter as modern Harleys move from ordinary used motorcycles into enthusiast-selected collector inventory.

Collectors typically value original paint, low owner count, unmodified or carefully documented mechanical condition, complete factory equipment and evidence that the motorcycle has not been over-customized. The strongest examples are the ones that still read as Harley-Davidson built them: blacked-out Fat Boy S trim, 110B engine, proper wheels, ABS and cruise control, with the stock take-off parts retained if tasteful modifications have been made.

Its market language is also specific. Enthusiasts search for Fat Boy S, FLSTFBS, Twin Cam 110 Fat Boy, 110B Softail and last Twin Cam Fat Boy. Those are not just SEO phrases; they are the shorthand buyers use when trying to separate this motorcycle from standard Fat Boys, Fat Boy Lo models and the later Milwaukee-Eight FLFBS.

Cultural Relevance

The Fat Boy name carried enormous cultural weight long before the S model arrived. The original FLSTF became one of Harley-Davidson's most recognizable modern silhouettes, helped by its solid-disc wheels, substantial front end and association with 1990s cruiser culture. The FLSTFBS did not create that identity, but it sharpened it for the final Twin Cam years.

Unlike many historically significant Harleys, the Fat Boy S has no meaningful racing or military service record. Its cultural role belongs to the factory-custom side of Harley-Davidson history: the period when buyers increasingly expected blacked-out finishes, larger engines and upgraded equipment directly from the showroom floor. It reflects the same customer logic that made factory performance cruisers and dark-custom models commercially important in the 2010s.

For club and owner culture, the Fat Boy S occupies a useful middle ground. It is modern enough to ride regularly, simple enough in layout to be understood by experienced Harley technicians, and visually tied to the older Fat Boy lineage. That combination gives it broader appeal than many short-lived trim variants.

FAQs

What years was the Harley-Davidson FLSTFBS Fat Boy S produced?

The FLSTFBS Fat Boy S was produced for the 2016 and 2017 model years. It belongs to the final Twin Cam Softail period before the redesigned Milwaukee-Eight Softail platform arrived for 2018.

What engine is in the 2016-2017 Fat Boy S?

The Fat Boy S uses the air-cooled Screamin' Eagle Twin Cam 110B, a counterbalanced 45-degree pushrod V-twin displacing 110 cu in, or 1801 cc. The B designation is important because it identifies the counterbalanced Softail version of the Twin Cam engine.

How much horsepower does a Fat Boy S make?

Harley-Davidson did not publish a regular factory horsepower figure for the FLSTFBS in the way many manufacturers publish peak horsepower. Factory specifications commonly list 108 ft-lb of torque at 3000 rpm in U.S. trim. Dyno horsepower figures vary by motorcycle, exhaust, intake, calibration and test method.

How can I tell a real FLSTFBS from a modified standard Fat Boy?

Start with the model code and documentation, then confirm the factory Twin Cam 110B engine, Fat Boy S equipment, blacked-out finish, ABS, cruise control and correct Softail chassis details. Do not rely on dark paint, aftermarket exhausts or Screamin' Eagle accessories alone, because many standard Fat Boys have been modified to resemble an S.

Is the Fat Boy S the same as the later FLFBS Fat Boy 114?

No. The FLSTFBS is a 2016-2017 Twin Cam Softail with the 110B engine. The FLFBS Fat Boy 114 belongs to the 2018-on redesigned Softail generation and uses the Milwaukee-Eight 114 engine with a different frame and suspension architecture.

What are the main mechanical concerns when buying a Fat Boy S?

Inspect the cam chest, lifters, primary drive, compensator, clutch, ABS service history and evidence of correct tuning after intake or exhaust changes. The 110B is a strong engine, but poorly documented modifications and heat-related neglect can turn a desirable motorcycle into an expensive project.

Is the 2016-2017 Fat Boy S collectible?

It is collectible as a late Twin Cam Softail variant rather than as a rare antique. The best examples are original or carefully documented, retain factory equipment and clearly present as true FLSTFBS motorcycles. Its two-year production span and factory 110B engine give it a stronger identity than many ordinary late-model cruisers.

Collector Takeaway

The 2016-2017 FLSTFBS Fat Boy S matters because it is the Fat Boy at the far edge of the Twin Cam Softail idea: the old visual grammar of the solid-wheel Softail cruiser, combined with the largest regular-production counterbalanced Twin Cam engine fitted to the model. It is not historically important because it raced, served in uniform or introduced a new chassis. It is important because it closed a chapter.

For the serious Harley collector, the right Fat Boy S is a disciplined purchase: correct code, correct 110B engine, factory finish, records, sensible modifications or none at all. In a Fat Boy family crowded with lookalikes, anniversary trims and owner-built customs, the FLSTFBS has a clean identity. It is the two-year, blacked-out, Twin Cam 110B Fat Boy, and that specificity is exactly why it will remain the one late Twin Cam Fat Boy enthusiasts keep calling out by code.