Positioning:
Essential diagnostic and repair resource for owners and technicians of the iconic Harley-Davidson FLH Shovelhead from 1981.
Comparison:
Offers in-depth technical data exceeding basic owner's manuals, providing the necessary detail for DIY repairs and professional servicing.
Features:
Detailed diagrams, step-by-step instructions, specifications, and troubleshooting guides critical for maintaining and repairing the Shovelhead engine and chassis.
Engine:
Shovelhead OHV V-Twin, Carburetion (Keihin/Linkert), Ignition System (Points/Electronic), Lubrication System, Cooling (Air)
Transmission:
4-Speed Constant Mesh, Clutch System, Primary Drive
Drivetrain:
Final Drive (Belt/Chain), Swingarm, Drive Sprockets
Chassis:
Frame, Suspension (Front Forks, Rear Shocks), Steering Headset
Brakes:
Front Disc Brake, Rear Drum Brake, Hydraulic System
Electrical:
Wiring Diagrams, Charging System (Alternator/Generator), Starting System (Starter Motor, Solenoid), Lighting System, Instruments, Battery
Bodywork:
Fuel Tank, Fenders, Seat, Handlebars, Controls, Exhaust System
Maintenance:
Oil Changes, Filter Replacements, Chain Adjustment, Spark Plug Service, Brake Fluid Flush, Battery Care, Lubrication Points
Troubleshooting:
Engine Starting Issues, Performance Problems, Electrical Faults, Braking System Malfunctions, Transmission Difficulties
Repair:
Engine Rebuilds, Transmission Overhauls, Fork Seal Replacement, Brake Caliper Rebuilds, Electrical Component Replacement
Diagnostics:
Component Testing, Fault Finding Charts, Symptom Analysis
Depth:
Comprehensive coverage from basic maintenance to detailed component overhaul and advanced diagnostic procedures.
PDF Quality:
High-resolution, searchable text, printable pages.
Printability:
Designed for clear printing of individual pages or sections.
Binding:
N/A (Digital PDF Download)
Paper Type:
N/A (Digital PDF Download)
Engine Type:
Harley-Davidson Shovelhead, Air-Cooled, 45-degree V-Twin
Displacement:
74 cubic inches (1212cc) and 80 cubic inches (1310cc) variants likely.
Bore X Stroke:
Typically 3.4375 in x 4.25 in (74ci) or 3.5 in x 4.25 in (80ci)
Compression Ratio:
Approximately 7.0:1 to 8.0:1 depending on specific engine variant and piston type.
Horsepower Estimate:
Approximately 55-65 HP
Torque Estimate:
Approximately 70-80 ft-lbs
Carburetor:
Keihin butterfly or Linkert carburetor (depending on specific build/options), with potential for aftermarket upgrades.
Fuel Type:
Unleaded gasoline (minimum 87 octane recommended, premium may be preferred for optimal performance).
Ignition Type:
Dual ignition system (dual spark plugs per cylinder) with breaker points and condenser or early electronic ignition (e.g., points replacement kits).
Oil Type:
Harley-Davidson 20W50 or equivalent V-Twin specific oil (e.g., SYN3 or similar).
Oil Capacity:
Approximately 3 US quarts (2.8 liters) for engine oil.
Oil Filter Part Number:
OEM 63814-71, or equivalent aftermarket (e.g., Fram PH7317, K&N HP-1008).
Type:
4-Speed Constant Mesh, Foot Shift, Hand Clutch
Gear Ratios:
Specific ratios vary but typically include: 1st Gear: ~9.17:1, 2nd Gear: ~6.5:1, 3rd Gear: ~4.8:1, 4th Gear: ~3.5:1 (These are approximate and can vary).
Fluid Type:
Primary chaincase lubricant (e.g., Harley-Davidson Primary Chaincase Lubricant, Spectro HD Primary Fluid, or a dedicated V-twin primary oil).
Fluid Capacity:
Approximately 24 US fluid ounces (0.7 liters) for the primary chaincase.
Wheelbase:
Approximately 60.6 inches (1539 mm)
Length:
Approximately 90-95 inches (2286-2413 mm)
Seat Height:
Approximately 28-30 inches (711-762 mm), unladen.
Dry Weight:
Approximately 600-650 lbs (272-295 kg)
Gross Vehicle Weight Rating:
Typically around 950-1000 lbs (431-454 kg)
Crash Test Results:
Not applicable for this era of motorcycle; safety features are mechanical and rider-focused.
Braking:
Single front disc brake, rear drum brake. ABS was not available.
Suspension:
Telescopic front forks with hydraulic damping, rear swingarm with dual adjustable shock absorbers.
Lighting:
Headlight, tail light, brake light, turn signals.
Controls:
Handlebar controls for throttle, clutch, front brake, ignition, lights, and horn.
Features:
None (This is a 1981 model; infotainment systems were not present. Instruments typically include speedometer, odometer, ammeter, and indicator lights.)
Features:
None (No electronic driver assistance systems).
Features:
None (No integrated connectivity features).
Oil Change:
Every 2,000-3,000 miles or annually, whichever comes first.
Spark Plugs:
Inspect and clean/gap every 2,000-3,000 miles. Replace as needed.
Primary Chain Tension:
Check and adjust every 2,000-3,000 miles.
Brake Fluid:
Inspect and flush/replace every 12-24 months.
Wheel Bearings:
Repack/inspect every 10,000-15,000 miles or as needed.
Engine Oil:
Harley-Davidson 20W50 or equivalent, API SF/SG rated.
Primary Oil:
Dedicated primary chaincase lubricant (e.g., Harley-Davidson Primary Chaincase Lubricant or similar).
Transmission Oil:
Harley-Davidson 80W90 Hypoid gear oil or equivalent (often the same as primary oil, check manual for specifics).
Fork Oil:
Harley-Davidson Type 'E' or 'K' fork oil, or equivalent (e.g., Bel-Ray 10W).
Engine:
Oil leaks (pushrod tubes, crankcase seals), valve guide wear, ignition system reliability (points/condenser), carburetor tuning issues, potential for oil dilution in crankcase.
Transmission:
Clutch adjustment and wear, potential for hard shifting, starter solenoid issues.
Electrical:
Aging wiring harnesses, charging system output inconsistencies, battery drain issues.
Chassis:
Fork seal leaks, worn wheel bearings, shock absorber degradation.
Heritage:
Harley-Davidson has a long-standing heritage of producing V-twin motorcycles for law enforcement, touring, and civilian use since the early 20th century.
Evolution:
The FLH series, specifically with the Shovelhead engine, represents a significant era for Harley-Davidson, evolving from earlier Panhead and Knucklehead designs. The 1981 model year falls towards the end of the Shovelhead era, just before the introduction of the Evolution engine.
Production Years:
Shovelhead engine production ran from 1966 to 1984. The FLH designation has been used for Harley-Davidson touring models for decades.
Manufacturing Location:
Milwaukee, Wisconsin, USA (Harley-Davidson's primary manufacturing location).
Market Impact:
The Shovelhead engine, despite its challenges, is considered an iconic engine in Harley-Davidson history, a symbol of a specific era of American motorcycling.
Reliability Perception:
While known for character and power, Shovelheads from this era are often perceived as requiring more hands-on maintenance and attention than later models.
Certification:
N/A (Motorcycle certification standards were different in 1981).
