🏷️ Basic Information

Make:

Harley-Davidson

Model:

FLSTF Fat Boy

Generation:

First Generation Softail Fat Boy

Codes:

FLSTF (Fat Boy)

Model Variant:

Fat Boy

👋 Introduction

Category:

Cruiser Motorcycle

Target Audience:

Owners and technicians specializing in Harley-Davidson motorcycles, particularly the Softail platform.

Historical Context:

The FLSTF Fat Boy, launched in 1990, quickly became an icon, defined by its solid-cast aluminum wheels, wide front fork, and distinctive 'Fat' styling, paying homage to the bob-job motorcycles of the 1940s. It was a significant departure in styling for Harley-Davidson at the time.

Design Philosophy:

Emphasis on classic styling, powerful V-twin engine, and comfortable cruiser ride.

Iconic Elements:

Solid disc wheels (front and rear), large headlight nacelle, wide handlebars, teardrop fuel tank, Fat Boy badging.

📋 Manual Details

Coverage Years:

1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999

Chassis Platform:

Softail

Estimated Page Count:

Estimated 600-800 pages (typical for comprehensive service manuals of this era)

Manual Type:

Service Repair Manual / Workshop Manual

Language:

English

Format:

PDF

📖 Manual Coverage

Engine:

V-Twin Evolution (1340cc/80ci), engine overhaul, disassembly, assembly, tuning, troubleshooting, component identification.

Transmission:

5-speed Cruise Drive transmission, gearbox overhaul, clutch service, shift mechanism repairs, fluid maintenance.

Fuel System:

Carburetor (likely Keihin CV 40mm), fuel delivery, fuel tank service, fuel lines, fuel pump (if applicable).

Ignition System:

Electronic ignition system, spark plugs, ignition coils, timing adjustment, troubleshooting ignition faults.

Electrical System:

Wiring diagrams, lighting systems (headlight, taillight, turn signals), battery, charging system (alternator, stator, regulator/rectifier), starter motor, electrical component testing and repair.

Braking System:

Front and rear disc brakes, brake caliper service, master cylinder overhaul, brake pad replacement, brake fluid flushing and bleeding, hydraulic system troubleshooting.

Suspension:

Front telescopic forks (Show Showa), rear swingarm with concealed shock absorbers, fork seal replacement, shock absorber service, suspension tuning, lubrication.

Frame And Bodywork:

Frame inspection, body panel removal and installation, fender service, fuel tank mounting, seat service, chrome component care.

Wheels And Tires:

Wheel bearing service, tire replacement, wheel balancing, spoke tension adjustment (if applicable to specific wheel types).

Exhaust System:

Exhaust pipe removal and installation, muffler service, exhaust gasket replacement, troubleshooting exhaust leaks.

Routine Maintenance:

Oil changes, filter replacements, spark plug checks, chain lubrication/adjustment (if applicable, though most Softails of this era had belt drive), battery maintenance, tire pressure checks, brake inspection.

Troubleshooting:

Diagnostic flowcharts, common problems and their solutions for engine, electrical, and mechanical systems.

Repair And Overhaul:

Detailed step-by-step instructions for rebuilding engine components, transmission, carburetor, brake systems, and suspension.

Wiring Diagrams:

Comprehensive electrical schematics for all model years covered, aiding in diagnosis and repair of electrical issues.

Special Tools:

Identification and usage of specialized tools required for specific repair procedures.

Depth:

Comprehensive workshop level coverage suitable for professional mechanics and experienced DIY enthusiasts. Covers everything from routine maintenance to complete engine and transmission rebuilds.

📊 Manual Specifications

File Format:

PDF

Searchability:

Searchable text-based PDF for quick access to specific information.

Print Quality:

Printable pages for workshop use.

Binding Type:

N/A (PDF format)

Paper Type:

N/A (PDF format)

⚙️ Engine Specifications

Engine Family:

Harley-Davidson Evolution (known as 'Evo')

Displacement:

1339cc (81.8 cubic inches)

Configuration:

Air-cooled, 45-degree V-twin

Bore X Stroke:

3.498 in x 4.25 in (88.8 mm x 108 mm)

Compression Ratio:

8.3:1 (typical for this era)

Valve Train:

Overhead valve (OHV), 2 valves per cylinder, pushrod actuated.

Horsepower:

Approximately 65-70 HP (estimated, actual figures vary slightly by year and tuning)

Torque:

Approximately 76-80 ft-lbs @ 3200 RPM (estimated)

Carburetor Model:

Keihin CV 40mm (Constant Velocity)

Fuel Type:

Unleaded gasoline, minimum 87 octane

Oil Type:

Harley-Davidson SAE 20W50 Motorcycle Oil (or equivalent API CG-4 rated diesel engine oil, per some older specs) or a specific V-twin motorcycle oil.

Oil Capacity:

3.5 US quarts (3.3 liters) with filter change (check manual for exact specification).

🔧 Transmission

Type:

5-speed constant mesh, manual transmission

Primary Drive:

Duplex chain, wet clutch

Final Drive:

Belt drive (38mm width, 132T belt)

Optional Gear Ratios:

Standard gear ratios, no factory options mentioned for this model and year range.

Clutch Type:

Wet, multi-plate, diaphragm spring

Transmission Fluid:

Harley-Davidson Formula + Transmission & Primary Chaincase Lubricant (or equivalent SAE 85W-140 API GL-5 gear oil for primary/transmission). Check manual for specifics.

📐 Dimensions

Length:

Approximately 93.0 inches (2362 mm)

Width Handlebar:

Approximately 36.0 inches (914 mm)

Height:

Approximately 47.0 inches (1194 mm)

Wheelbase:

Approximately 63.7 inches (1618 mm)

Ground Clearance:

Approximately 4.7 inches (119 mm)

Dry Weight:

Approximately 649 lbs (294 kg)

Gross Vehicle Weight Rating:

Approximately 1000 lbs (454 kg)

Fuel Capacity:

4.0 US gallons (15.1 liters)

Seat Height:

Approximately 26.0 inches (660 mm)

🛡️ Safety Features

Crash Test Ratings:

N/A (Motorcycles are not subject to the same standardized crash testing as automobiles.)

Braking System:

Dual disc front brakes, single disc rear brake.

Lighting:

Halogen headlight, integrated front and rear turn signals, stop/tail light.

Frame Construction:

Steel frame with Softail rear suspension design.

Tire Type:

Tubeless tires on solid cast wheels.

💡 Technology Features

Infotainment System:

None. These models did not feature integrated infotainment systems; audio systems were aftermarket additions.

Driver Assistance Features:

None. Focus is on traditional motorcycling experience.

Connectivity Features:

None.

Headlight Type:

Halogen

Ignition Type:

Electronic ignition with vacuum and RPM advance.

🔧 Maintenance

Oil Change Interval:

Every 5,000 miles (8,000 km) or 6 months, whichever comes first (typical for this era).

Primary Chaincase Oil Change:

Every 10,000 miles (16,000 km) or 12 months.

Spark Plug Inspection:

Every 10,000 miles (16,000 km).

Brake Fluid Flush:

Every 2 years or as needed based on inspection.

Belt Tension Check:

Every 10,000 miles (16,000 km).

Engine Oil Grade:

SAE 20W50 Motorcycle Oil (or Harley-Davidson branded oil)

Transmission Primary Fluid Grade:

Harley-Davidson Formula + or SAE 85W-140 API GL-5 Gear Oil

Brake Fluid Type:

DOT 4

Common Wear Items:

Clutch plates, brake pads, fork seals, wheel bearings, battery, starter solenoid.

Potential Engine Issues:

Pushrod tube leaks (early Evo models), oil leaks from engine seals, carburetor adjustment issues (CV carb sensitivity to tuning).

Electrical Concerns:

Wiring harness degradation over time, regulator/rectifier failures, headlight bulb issues.

Belt Drive Considerations:

Belt tension is critical; incorrect tension can lead to premature belt or pulley wear. Check for debris in the belt guard.

📚 Vehicle History

Founding:

Harley-Davidson Motor Company founded in 1903.

Reputation:

Iconic American motorcycle manufacturer, known for its V-twin engines, distinctive styling, and rider community.

Introduction Year:

1990

Influences:

Inspired by the 'bob-job' custom motorcycles of the post-WWII era, particularly the appearance of the 1949 Harley-Davidson Hydra-Glide.

Softail Platform:

Part of the Softail family, characterized by a hidden rear suspension system that mimics the look of a hardtail frame.

Evolution Engine:

This period marks the widespread adoption of the Evolution (Evo) engine, which replaced the Shovelhead and Ironhead engines, offering improved reliability and performance.

Production Period:

1990-1999 (as covered by this manual). The Fat Boy model continued with updates in subsequent years.

Manufacturing Location:

United States (primarily Milwaukee, Wisconsin and York, Pennsylvania)