Positioning:
Essential reference for owners and independent mechanics seeking to maintain and repair the iconic Harley-Davidson FXB Shovelhead.
Analogy:
As the primary factory service document, it's the definitive source, surpassing generic Haynes or Clymer manuals in detail for specific Harley-Davidson procedures.
Essentiality:
Provides critical torque specs, clearances, and troubleshooting guidance specific to the Shovelhead engine and FXB platform.
Value Proposition:
Empowers users with the knowledge to perform complex maintenance and repairs, saving on dealership costs and ensuring proper operation.
Engine:
Shovelhead 80 cubic inch (1340cc) V-twin, including top end, bottom end, lubrication, cooling, ignition, and fuel systems.
Transmission:
4-speed constant mesh, primary drive, clutch, shifter linkage, and related components.
Electrical:
Wiring diagrams, charging system (alternator, regulator), ignition system (points, coil, spark plugs), lighting, starting system (starter motor, solenoid), and accessories.
Chassis:
Frame, front suspension (forks, steering head), rear suspension (shocks, swingarm), wheels, tires, and braking systems (front and rear).
Bodywork And Trim:
Fenders, fuel tank, seat, handlebars, controls, exhaust system, and related fasteners and trim.
Maintenance:
Regular servicing, oil changes, filter replacements, chain adjustment, tire pressure, and general upkeep.
Troubleshooting:
Diagnostic procedures for common problems, fault finding charts, and symptom analysis.
Repair And Rebuild:
Step-by-step instructions for disassembly, inspection, repair, and reassembly of all major vehicle components.
Adjustments:
Carburetor tuning, ignition timing, clutch adjustment, brake adjustments, and suspension settings.
Diagnostics:
Procedures for checking and diagnosing electrical faults, engine performance issues, and mechanical problems.
Depth:
Comprehensive, covering basic maintenance to full engine and transmission rebuilds, including detailed torque specifications, clearances, and special tool requirements.
Engine Type:
Air-cooled, 45-degree V-twin, OHV (Shovelhead)
Displacement:
80 cubic inches (1340 cc)
Bore X Stroke:
3.4375 in x 4.25 in (87.31 mm x 107.95 mm)
Compression Ratio:
Approximately 8.0:1
Horsepower:
Estimated 60-70 HP (at crankshaft, varies by tuning)
Torque:
Estimated 75-85 ft-lbs (at crankshaft, varies by tuning)
Carburetor:
Typically a Keihin butterfly or Linkert carburetor, or potentially a S&S Super E/G as an aftermarket option.
Fuel Type:
Unleaded gasoline, minimum 87 octane recommended.
Oil System:
Dry Sump system with oil tank mounted separately (typically in the oil tank itself).
Oil Type:
Harley-Davidson recommended motorcycle oil, typically a straight-weight 20W-50 or similar API SG/SH rated oil for this era.
Type:
4-speed constant mesh, foot-shift, hand-clutch operation.
Transmission Variants:
No factory optional transmissions for the FXB model in 1981; aftermarket 5-speed conversions were common.
Primary Drive:
Heavy-duty multi-plate wet clutch, chain drive to transmission.
Final Drive:
Belt drive (FXB featured belt drive, unlike chain-drive FXWG models).
Transmission Fluid:
Typically Harley-Davidson recommended transmission lubricant or equivalent 80W-90 gear oil.
Wheelbase:
Approximately 62.5 inches (1588 mm)
Length:
Approximately 88 inches (2235 mm)
Seat Height:
Approximately 28 inches (711 mm) unladen
Dry Weight:
Approximately 550-600 lbs (250-272 kg)
Fuel Capacity:
Approximately 3.5 gallons (13.2 liters)
Safety Ratings:
N/A (Motorcycle safety ratings are not typically provided in the same manner as automobiles).
Brakes:
Hydraulic disc brakes front and rear (single disc front, single disc rear).
Tires:
Tubed tires, standard sizes typically 3.50-19 front and 5.10-16 rear.
Lighting:
Headlight, taillight, brake light, turn signals, and running lights as per regulations of the time.
Infotainment System:
N/A (Minimal to no electronic infotainment features on 1981 models; focus is on mechanical systems).
Driver Assistance Features:
N/A (No electronic driver assistance features on this model).
Connectivity Features:
N/A (No electronic connectivity features).
Oil Change Interval:
Typically every 2,000-3,000 miles or annually.
Primary Chain Adjustment:
As needed, typically checked every 1,000-2,000 miles or if clutch slippage is detected.
Spark Plug Replacement:
Approximately every 10,000-15,000 miles, or as per manual recommendations.
Engine Oil Capacity:
Approximately 3 quarts (2.8 liters) with filter change.
Transmission Oil Capacity:
Approximately 1 quart (0.95 liters).
Primary Chain Case Oil:
Typically shared with the engine oil, or a specific primary oil can be used as per later models/preferences.
Oil Leaks:
Common due to aging seals and gaskets; manual will detail gasket replacement procedures.
Carburetor Tuning:
Shovelheads can be sensitive to carburetor adjustment; manual provides tuning procedures.
Ignition Timing:
Points ignition requires periodic adjustment; manual details timing procedures.
Pushrod Tubes:
Potential for leaks at pushrod tube seals; manual covers inspection and replacement.
Heritage:
Harley-Davidson, founded in 1903, is an American icon renowned for its V-twin motorcycles and cruiser heritage.
Shovelhead Era:
The Shovelhead engine was produced from 1966 to 1984, evolving from the Panhead and preceding the Evolution (Evo) engine. The FXB was a specific configuration within this era.
Fxb Introduction:
The FXB, part of the 'Sturgis' and similar FX models, was introduced to offer a more refined and comfortable cruiser experience, often featuring a factory belt drive.
1981 Context:
1981 marked a transition period for Harley-Davidson, with ongoing development of the Shovelhead platform and preparations for the forthcoming Evolution engine.
Iconic Status:
The Shovelhead engine itself is considered an icon of American motorcycle engineering and culture.
Performance Ratings:
While not receiving formal 'awards,' the 1981 FXB was praised for its torque and cruiser comfort for its era.
Certification Standard:
Manufactured to Harley-Davidson's internal quality standards and applicable US safety regulations for motorcycles of the period.
