Model:
FL, FX Series (4-Speed)
Applicable Models:
FLH, FLHS, FXB, FXSB, FXE, FXEF, FXS, FXWG, FXST
Model Years Covered:
1978, 1979, 1980, 1981, 1982, 1983, 1984
Engine Type Code:
4-Cycle, 45 Degree V-Twin
Market Position:
Essential reference for owners and mechanics maintaining classic Harley-Davidson Big Twin motorcycles from the late 70s and early 80s, a pivotal era for the brand.
Competitive Analysis:
This manual provides in-depth, specific guidance for the 4-speed transmission era Big Twins, differentiating it from owner's manuals or generic repair guides. It is crucial for preserving the authenticity and functionality of these iconic machines.
Key Features:
Includes detailed technical drawings, exploded views, torque specifications, and troubleshooting trees critical for accurate repair. Covers the transition to early Evolution engines and the prevalent 4-speed gearboxes.
Primary Coverage:
Complete mechanical and electrical repair and maintenance for 1978-1984 Harley-Davidson FL and FX series motorcycles with 4-speed transmissions.
Secondary Coverage:
Troubleshooting, routine maintenance, specifications, component identification, disassembly, assembly, and system overhauls.
Estimated Page Count:
Varies by publisher; typically 300-500 pages for a comprehensive service manual.
Manual Type:
Factory-Style Repair/Service Manual
Format:
Print (Paperback/Spiral-bound)
Engine:
Detailed coverage of 1200cc and 1340cc (80ci) Evolution V-twin engines, including top end (cylinders, heads, valves), bottom end (crankshaft, connecting rods, bearings), timing, lubrication, and cooling systems.
Transmission:
Comprehensive coverage of the 4-speed constant mesh transmission, including clutch, gearbox internals, shifting mechanisms, and primary drive.
Fuel System:
Carburetor service (e.g., Keihin Butterfly, CV type), fuel pump, fuel lines, and fuel tank maintenance.
Electrical System:
Ignition system (points, electronic), charging system (alternator/generator, regulator), starter system, lighting, wiring diagrams, and troubleshooting electrical faults.
Brakes:
Front and rear brake systems, including hydraulic components (master cylinders, calipers, lines), brake pads, and rotor specifications.
Suspension:
Front fork (telescopic), rear shock absorbers, and swingarm service, including oil changes and seal replacement.
Frame And Bodywork:
Frame inspection, mounting hardware, fenders, fuel tank, seat, handlebars, and control cables.
Wheels And Tires:
Wheel bearing service, spoke maintenance, tire replacement guidelines, and wheel alignment checks.
Routine Maintenance:
Oil changes, filter replacements, chain adjustment, spark plug replacement, battery maintenance, and air filter cleaning/replacement.
Troubleshooting:
Systematic diagnostic procedures for common and uncommon problems across all major motorcycle systems.
Engine Rebuild:
Step-by-step instructions for engine disassembly, component inspection, machining recommendations, and reassembly.
Transmission Overhaul:
Detailed procedures for transmission disassembly, gear inspection, bearing replacement, and reassembly.
Electrical Diagnosis:
Wiring diagrams with component identification, troubleshooting flowcharts, and specific diagnostic tests for electrical circuits.
Carburetor Tuning:
Adjustment procedures, jetting information, and rebuild instructions for various carburetor models.
Brake Service:
Bleeding procedures, caliper piston replacement, master cylinder rebuild, and pad replacement.
Fork Seal Replacement:
Step-by-step guide for replacing front fork seals and servicing fork oil.
Depth Level:
Comprehensive: Covers basic to advanced repair and overhaul procedures, including diagnostic charts and specifications for expert-level work.
Engine Family:
Shovelhead (1978-1980) and early Evolution Big Twin (1984 for certain models, though main evolution is 1984 onwards).
Engine Displacement:
1200cc (74 cu in) and 1340cc (80 cu in)
Engine Configuration:
Air-cooled, 45-degree V-twin
Bore X Stroke 1200Cc:
3.4375 in x 4.125 in (87.31 mm x 104.78 mm)
Bore X Stroke 1340Cc:
3.499 in x 4.250 in (88.88 mm x 107.95 mm)
Compression Ratio Typical:
Approximately 7.0:1 to 8.0:1 (varies by year and model)
Horsepower Estimated:
Approx. 55-65 HP (at crankshaft, varies by year/tuning)
Torque Estimated:
Approx. 65-75 ft-lbs (at crankshaft, varies by year/tuning)
Carburetor Examples:
Keihin Butterfly, Keihin CV (Constant Velocity), Mikuni VM Series (less common but possible)
Fuel Type Recommended:
Unleaded gasoline (87 octane or higher, check specific model recommendations)
Fuel Tank Capacity:
Typically 3.5 to 5.0 gallons (13.2 to 18.9 liters), depending on the model's specific tank.
Transmission Type:
4-Speed Constant Mesh
Gear Ratios Typical:
1st: ~2.44:1, 2nd: ~1.57:1, 3rd: ~1.11:1, 4th: 1.00:1 (Specific ratios may vary slightly by year/model)
Clutch Type:
Wet multi-plate, hydraulically operated (later models) or cable operated (earlier in the range).
Primary Drive:
Chain drive (enclosed in primary cover), often with a compensator sprocket.
Transmission Oil Type:
Dedicated transmission oil (e.g., Harley-Davidson 80W-90 or equivalent API GL-4 gear oil). Avoid GL-5 due to potential damage to yellow metals.
Wheelbase:
Typically around 60-62 inches (1524-1575 mm), depending on the specific FL or FX model.
Length:
Varies by model, typically 88-90 inches (2235-2286 mm).
Dry Weight:
Around 580-650 lbs (263-295 kg), depending on model and equipment.
Gross Vehicle Weight Rating:
Not typically published as a strict GVWR like cars, but rider and payload capacity are factors.
Oil Change Engine:
Every 2,000-3,000 miles (3,200-4,800 km) or 6 months, whichever comes first. Check manual for specific interval.
Transmission Oil Change:
Every 5,000-10,000 miles (8,000-16,000 km) or annually. Check manual for specific interval.
Primary Drive Chain Lube:
Every 500-1000 miles (800-1600 km) and after washing or riding in rain. Chaincase oil level check every 2000 miles.
Spark Plug Replacement:
Every 5,000-10,000 miles (8,000-16,000 km). Inspect and gap at oil changes.
Engine Oil Type Hd:
Harley-Davidson 20W-50 or equivalent API SG/SH rated oil for air-cooled V-twins.
Engine Oil Capacity:
Approx. 3 quarts (2.8 liters) for 1200cc, 4 quarts (3.8 liters) for 1340cc. Check dipstick/level check procedures.
Transmission Oil Spec:
Harley-Davidson 80W-90 Hypoid Gear Oil (API GL-4) or equivalent. Do not use GL-5.
Primary Chaincase Oil:
Often shared with transmission oil or a specific primary chaincase lubricant. Check manual for year-specific recommendations.
Fork Oil Type:
Specific fork oil viscosity (e.g., 10W or 15W) depending on fork type and rider preference. Check manual for type and capacity.
Brake Fluid Type:
DOT 4 recommended for hydraulic systems. Check reservoir cap.
Shifter Lever Play:
Wear in the shifter linkage or drum can lead to sloppy shifting. Requires adjustment or replacement of worn parts.
Oil Leaks:
Common in older bikes. Potential sources include primary cover gasket, transmission seals, crankcase seals, and rocker box gaskets. The manual provides procedures to address these.
Carburetor Tuning Issues:
Difficult starting, poor idle, hesitation can be due to worn carb components, incorrect jetting, or air leaks. Manual details tuning and rebuilds.
Ignition System Problems:
Points ignition can drift or wear, affecting timing. Early electronic ignitions can also fail. Manual covers diagnosis and replacement.
Rear Brake Wear:
Rear brake pads and rotors can wear significantly with use. Regular inspection and replacement are necessary.
Brand Heritage:
Harley-Davidson, founded in 1903, has a long and storied history of building powerful, distinctive V-twin motorcycles, becoming an icon of American motorcycling culture.
Model Evolution:
The FL and FX lines represent the Big Twin platform. The late 70s saw the tail end of the Shovelhead engine era and the introduction of the Evolution (often called 'Evo') engine in 1984. The 4-speed transmission was a staple for decades before the advent of the 5-speed.
Production Period:
This manual covers the 1978-1984 production years, a transitional period for Harley-Davidson, marked by corporate changes and technological advancements.
Manufacturing Location:
United States (Milwaukee, Wisconsin and York, Pennsylvania primarily).
