Market Position:
Essential resource for owners and mechanics of 1978 Harley-Davidson FX Shovelhead motorcycles, catering to restoration, maintenance, and repair needs.
Competitive Analysis:
This manual provides the critical, factory-level information needed to properly service and maintain the iconic Shovelhead engine and chassis, surpassing generic repair guides and often scarce original documentation.
Key Features:
Provides detailed diagrams, step-by-step instructions, and essential technical data, enabling users to perform complex repairs and maintenance with confidence.
Systems Covered:
Engine, Carburetion, Ignition, Fuel System, Transmission, Drivetrain, Frame, Suspension, Brakes, Electrical System, Lighting, Bodywork, Troubleshooting, Specifications
Page Count:
Estimated 300-400 pages (typical for a comprehensive service manual of this era, exact count depends on specific publication)
Manual Type:
Service Repair Manual
Engine Systems:
Detailed breakdown of the Shovelhead V-twin engine, including cylinder heads, pistons, rings, connecting rods, crankshaft, camshafts, valve train, oil pump, and cooling systems (air-cooled specific).
Fuel And Carburetion:
In-depth coverage of fuel tank, fuel lines, petcock, carburetors (e.g., Keihin Butterfly, Linkert depending on specific FX model variants), fuel pump operation, and tuning procedures.
Ignition And Electrical:
Comprehensive explanations of the ignition system (points, condenser, coil, spark plugs), charging system (generator/alternator, regulator), battery, starter motor, wiring diagrams, lighting circuits, horn, and accessory wiring.
Transmission And Drivetrain:
Detailed instructions for the 4-speed constant mesh transmission, clutch operation, primary drive, final drive belt/chain, and associated components.
Chassis And Suspension:
Coverage of frame components, front fork assembly (e.g., Springer, Glide forks depending on FX variant), rear shock absorbers, swingarm, steering head bearings, and wheel bearings.
Brakes:
Service and repair procedures for the braking system, including front and rear brake assemblies (drum or disc depending on model year and configuration), master cylinders, calipers, brake lines, and adjustments.
Bodywork And Trim:
Information on fenders, fuel tank, seat, handlebars, controls, exhaust system, and other cosmetic and functional body components.
Maintenance Procedures:
Scheduled maintenance tasks such as oil changes, filter replacements, spark plug checks, chain/belt adjustments, brake adjustments, lubrication points, and general inspections.
Repair Procedures:
Step-by-step repair instructions for all major mechanical and electrical systems, including engine rebuilds, transmission overhauls, brake caliper replacement, fork seal replacement, and electrical component troubleshooting.
Troubleshooting Guides:
Diagnostic procedures and symptom-based troubleshooting charts for common issues related to starting, running, electrical problems, and braking.
Torque Specifications:
Detailed torque values for critical fasteners across all systems, essential for proper assembly and preventing component damage.
Depth Level:
Comprehensive. Covers everything from basic routine maintenance to complete engine and transmission overhauls, including detailed diagnostic procedures and component-level repair.
Engine Type:
Air-cooled, 45-degree V-twin
Engine Family:
Shovelhead
Displacement:
Typically 74 cubic inches (1200cc) for the FX model, but 80 cubic inches (1338cc) was also available in related models. Manual should clarify specific FX variants.
Horsepower Estimate:
Approx. 60-70 HP (Varies based on specific tuning, exhaust, and carburetors)
Torque Estimate:
Approx. 70-80 ft-lbs (Varies based on specific tuning)
Carburetor Types:
Commonly Keihin Butterfly (e.g., CV or PBI) or Linkert carburetors depending on original specifications and variations. Manual will detail specific types and their servicing.
Fuel Type:
Unleaded gasoline (Octane rating suitable for the era, manual will specify if leaded fuel was still recommended or if unleaded compatibility was introduced).
Engine Oil Change Interval:
Typically every 2,000-3,000 miles or 6 months, whichever comes first. Manual will provide exact recommendations.
Transmission Oil Change Interval:
Typically every 5,000-10,000 miles or annually. Manual will specify.
Primary Chain Case Oil Change Interval:
Typically every 5,000-10,000 miles or annually. Manual will specify.
Engine Oil Type:
Viscosity grades like SAE 20W-50 or SAE 50 are common for Shovelheads. Specific Harley-Davidson recommendations or equivalent API service classifications (e.g., SG or higher) will be detailed in the manual.
Transmission Oil Type:
Dedicated transmission fluid or specific viscosity gear oil, often Harley-Davidson brand or equivalent. Manual will list part numbers and specifications.
Primary Chain Case Oil Type:
Often primary lubricant or specific transmission fluid. Manual will detail the correct fluid and its capacity.
Known Issues Engine:
Oil leaks (common on Shovelheads), valve guide wear, lifter noise, potential for pushrod tube leaks. Manual provides solutions.
Known Issues Transmission:
Clutch adjustment, occasional shifting difficulties, input shaft seal leaks. Manual offers troubleshooting and repair.
Known Issues Electrical:
Wiring harness degradation over time, generator/alternator output issues, regulator failure. Manual provides wiring diagrams and diagnostic steps.
Brand Heritage:
Harley-Davidson, founded in 1903, is synonymous with American motorcycling culture. The Shovelhead engine, introduced in 1966, was a significant evolution in their V-twin design.
Model Evolution:
The FX series was introduced in 1971, bridging the gap between the traditional FL (Electra Glide) and XL (Sportster) models. The FX lineup featured the Shovelhead engine in various configurations (FX, FXE, FXS, FXWG) offering different styling and components.
Production Era:
The Shovelhead engine was produced from 1966 to 1984. The 1978 model year represents a mature stage of the Shovelhead's development.
Manufacturing Location:
Milwaukee, Wisconsin, USA
