🏷️ Basic Information

Make:

Harley-Davidson

Model:

FLSTF Fat Boy

Year:

2015

Model Code:

FLSTF

Generation Identifier:

Second Generation (2000-2017)

Vin Code:

1HD1

👋 Introduction

Market Position:

The Harley-Davidson FLSTF Fat Boy represents iconic American cruiser styling, offering a blend of classic aesthetics with modern V-twin performance. It targets riders seeking a distinctive, comfortable, and powerful riding experience, often associated with a lifestyle brand.

Competitive Analysis:

Competes with other large-displacement cruiser motorcycles from brands like Indian Motorcycles, Victory Motorcycles (now defunct but relevant to era), and select models from Japanese manufacturers that emulate the cruiser style.

Key Features:

Distinctive 'Fat' tire profile, large-diameter front fork, wide handlebars, chrome accents, powerful V-twin engine, comfortable riding position, a timeless design that evokes vintage styling.

Manual Value Proposition:

Essential for owners and independent repair shops seeking to perform comprehensive maintenance, diagnostics, and repairs on their 2015 Harley-Davidson FLSTF Fat Boy. Provides detailed, factory-authorized procedures for optimal vehicle upkeep and longevity.

📋 Manual Details

Primary Coverage:

Workshop Service Repair

Page Count:

626

Manual Type:

Factory Service Manual (FSM)

Language:

English

Format:

PDF (Instant Download)

📖 Manual Coverage

Engine System:

Engine assembly, disassembly, lubrication, cooling, fuel, ignition, exhaust, emissions control, performance tuning.

Transmission System:

Clutch, primary drive, transmission assembly (5-speed Cruise Drive), secondary drive (belt drive), lubrication, troubleshooting.

Chassis System:

Frame, suspension (front forks, rear shock absorbers), steering, wheels, tires, brakes (front and rear hydraulic disc), brake system bleeding, ABS operation.

Electrical System:

Battery, charging system (alternator, regulator), starting system (starter motor, solenoid), lighting (headlamp, tail lamp, turn signals), instrumentation, ignition switch, security system (Smart Security System), wiring diagrams, diagnostics.

Fuel System:

Fuel tank, fuel pump, fuel filter, fuel injectors, Electronic Control Module (ECM) tuning, throttle body, troubleshooting.

Bodywork And Trim:

Fenders, fuel tank, seat, handlebars, controls, mirrors, body panels, mounting hardware, cosmetic repairs.

Maintenance Procedures:

Routine inspections, oil changes, filter replacements, belt adjustments, brake pad replacement, spark plug replacement, cable adjustments, tire pressure checks.

Repair Procedures:

Engine rebuilds, transmission overhauls, suspension component replacement, brake caliper rebuilds, electrical component diagnosis and replacement, body panel repair and replacement.

Troubleshooting Diagnostics:

Diagnostic trouble codes (DTCs), symptom-based troubleshooting, component testing, electrical system diagnosis using multimeter and oscilloscope, fuel system diagnostics, ignition system analysis.

Special Tools Techniques:

Detailed descriptions and illustrations of specialized tools required for specific repair and maintenance procedures (e.g., clutch compression tool, flywheel holder, engine assembly stand).

Technical Depth:

Comprehensive. Covers from basic scheduled maintenance to complete engine and transmission rebuilds, advanced electrical diagnostics, and frame-level repairs.

📊 Manual Specifications

File Format:

PDF

Print Quality:

High-resolution scans, clear text, sharp images and diagrams. Optimized for digital viewing and printing.

Binding Type:

N/A (Digital PDF)

Paper Type:

N/A (Digital PDF)

Searchability:

Fully searchable text for quick access to specific information.

Interactivity:

Hyperlinked table of contents for easy navigation.

⚙️ Engine Specifications

Engine Type:

Air-cooled, Twin Cam 103™

Displacement:

103 cu. in. (1690 cc)

Bore X Stroke:

3.875 in. x 4.375 in. (98.4 mm x 111.3 mm)

Compression Ratio:

9.6:1

Valve Train:

Pushrod-actuated, overhead valves with hydraulic lifters; 2 valves per cylinder

Torque:

101 ft-lbs @ 3,500 RPM (approximate, may vary slightly by specific configuration and market)

Horsepower:

Not officially stated, but generally in the 70-80 HP range (crank).

Fuel Delivery:

Electronic Sequential Port Fuel Injection (ESPFI)

Fuel Type:

Premium unleaded gasoline, minimum 91 octane

Ignition System:

High-performance, electronic ignition with knock control.

Exhaust System:

Dual mufflers with catalytic converter (market dependent).

🔧 Transmission

Transmission Type:

6-speed Cruise Drive®

Gear Ratios:

1st: 9.315, 2nd: 6.454, 3rd: 4.774, 4th: 3.749, 5th: 3.209, 6th: 2.790 (typical values, may vary slightly)

Primary Drive:

Plated, wet, multi-plate clutch; chain drive

Secondary Drive:

Belt drive (70-tooth rear pulley)

Primary Fluid:

Harley-Davidson® FORMULA+ Transmission and Primary Chaincase Lubricant, or equivalent V-Twin transmission oil meeting Harley-Davidson specification.

Primary Fluid Capacity:

3.0 US qt (2.8 L)

📐 Dimensions

Length:

96.2 in. (2443 mm)

Seat Height Laden:

26.1 in. (663 mm)

Ground Clearance:

5.1 in. (130 mm)

Rake:

32 degrees

Trail:

5.2 in. (132 mm)

Dry Weight:

672 lbs (305 kg)

Weight In Running Order:

705 lbs (320 kg)

Gross Vehicle Weight Rating Gvwr:

1160 lbs (526 kg)

Fuel Capacity:

5.0 US gal. (18.9 L)

Front Tire:

Dunlop® D402F MH90-21 56H

Rear Tire:

Dunlop® D402 MU85B16 77H

Wheel Style:

Cast aluminum, steel laced wheels with solid disc rear

Wheel Bolt Pattern:

N/A (Hub center mounting)

🛡️ Safety Features

Safety Ratings:

Not applicable in the same manner as automotive vehicles. Focus is on rider safety features and compliance with road regulations.

Active Safety Features:

Anti-lock Braking System (ABS) available as an option, dual hydraulic disc brakes, responsive steering geometry.

Passive Safety Features:

Halogen headlamp, LED tail lamp, integrated turn signals, steel frame construction, rider-assist features (e.g., cruise control on some models/options).

Lighting System:

55W H4 Halogen headlamp, 5W/21W tail/stop lamp, 10W amber front/rear turn signal lamps.

💡 Technology Features

Infotainment System:

Base models may not have advanced infotainment. Premium models might feature a basic analog speedometer with integrated LCD screen for odometer, trip meter, clock, gear indicator, and diagnostics. Some custom options or aftermarket integrations may include audio systems.

Driver Assistance Features:

Optional Anti-lock Braking System (ABS). Cruise control may be available as an option or on higher trim levels.

Connectivity Features:

Limited to diagnostic port for electronic service tools. No inherent Bluetooth or smartphone integration on standard models.

Engine Management System:

Electronic Control Module (ECM) manages fuel injection, ignition timing, and other engine parameters. Diagnostics accessed via HD-LAN or proprietary diagnostic tools.

🔧 Maintenance

First Service:

1,000 miles (1,600 km) or 6 months, whichever comes first.

Subsequent Services:

Every 5,000 miles (8,000 km) or 12 months, whichever comes first. Engine oil and filter changes typically every 5,000 miles.

Engine Oil:

Harley-Davidson® SYN3® Full Synthetic Motorcycle Oil (SAE 20W50) or equivalent V-Twin motorcycle oil meeting Harley-Davidson specification (e.g., HD-360 SAE 20W50).

Engine Oil Capacity:

3.5 US qt (3.3 L) with filter change

Brake Fluid:

DOT 4 HD or equivalent DOT 4 brake fluid.

Fork Oil:

Harley-Davidson® Suspension Fluid (Type E) or equivalent 15W fork oil (specific viscosity depends on suspension type and rider preference, refer to manual).

Transmission Oil Type:

Harley-Davidson® FORMULA+ Transmission and Primary Chaincase Lubricant or equivalent V-Twin transmission oil.

Transmission Oil Capacity:

3.0 US qt (2.8 L)

Common Issues:

Potential for cam chain tensioner wear (especially on earlier Twin Cam engines, though improved by 2015), exhaust pipe leaks at the head, slight oil seepage from engine seals, ABS system sensitivity on rough surfaces, initial clutch engagement stiffness.

Oil Filter Part Number:

63796-77B (Harley-Davidson OEM) or equivalent aftermarket part.

Air Filter Part Number:

29000004 (Harley-Davidson OEM) or equivalent aftermarket part.

Spark Plug Part Number:

6R12 (NGK) or equivalent.

📚 Vehicle History

Brand Heritage:

Harley-Davidson, founded in 1903, is one of the most iconic American motorcycle manufacturers, known for its V-twin engines, distinctive styling, and a powerful brand culture that resonates globally.

Model Evolution:

The Fat Boy nameplate was first introduced in 1990. The 2015 model is part of the Softail family and features the Twin Cam 103 engine, a significant upgrade from earlier models. The 'Fat Boy' moniker refers to its broad front fork, massive front wheel, and overall robust appearance, inspired by elements from both Harley-Davidson and the DeLorean DMC-12.

Production Location:

York, Pennsylvania, USA and Kansas City, Missouri, USA (primary assembly locations for Harley-Davidson motorcycles).

🏆 Awards & Recognition

Motorcycle Awards:

While specific awards for the 2015 FLSTF Fat Boy are not as commonly publicized as automotive awards, Harley-Davidson motorcycles, particularly the Fat Boy lineage, consistently receive accolades for their iconic design, V-twin performance, and cultural impact within the motorcycle industry and lifestyle segment.

Customer Satisfaction Ratings:

Generally high among owners who appreciate the classic styling and riding experience. J.D. Power and Associates often survey motorcycle brands, and Harley-Davidson typically ranks well in certain segments, particularly in terms of brand loyalty and emotional appeal.