Positioning:
The 1978 Harley-Davidson FXS was a significant model in the FX line, often referred to as the 'Super Glide,' representing a blend of the FL dresser chassis with the lighter engine and sporty handling characteristics of the XL Sportster. It was positioned as a versatile cruiser, appealing to riders seeking a balance of comfort and performance.
Competitors:
In 1978, key competitors in the American motorcycle market included other Harley-Davidson models and offerings from American-made manufacturers like Indian (though its production was limited by this point). Internationally, Japanese manufacturers like Honda, Kawasaki, Yamaha, and Suzuki were gaining significant market share with their evolving technologies and diverse model ranges.
Features:
The Shovelhead engine provided characteristic V-twin torque, the FXS offered a comfortable riding position for its era, and its styling was a recognizable Harley-Davidson cruiser aesthetic.
Engine:
Detailed engine overhaul, including cylinder head, cylinders, pistons, connecting rods, crankshaft, camshaft, valve train, oil pump, and timing systems. Specific to Shovelhead V-twin air-cooled design.
Transmission:
Coverage of the 4-speed constant mesh transmission, including gear removal, inspection, and replacement. Explains shifting mechanisms and related components.
Clutch:
In-depth instructions for clutch assembly, adjustment, and component replacement, including clutch plates, hub, and pressure plate.
Electrical System:
Comprehensive coverage of the ignition system (points and condenser or early electronic), lighting, charging system (generator/alternator and regulator), and starter motor, supported by detailed wiring diagrams.
Fuel System:
Details on carburetor overhaul and adjustment (likely Keihin butterfly or Linkert), fuel tanks, fuel lines, and fuel filtration.
Suspension And Steering:
Covers front forks (likely FLH or Sportster type depending on FXS configuration), rear shock absorbers, swingarm, steering head bearings, and related components.
Brakes:
Information on front and rear brake systems, including disc brake caliper overhaul, hydraulic lines, master cylinders, and brake shoe inspection/replacement if applicable.
Frame And Bodywork:
While not explicitly listed as a major section, general information and repair procedures for frame components, fenders, tanks, and mounting hardware are typically included in factory manuals.
Repair Procedures:
Step-by-step instructions for complete disassembly and reassembly of all major vehicle components.
Maintenance Procedures:
Regularly scheduled maintenance tasks, fluid changes, lubrication points, and inspections.
Troubleshooting Guides:
Diagnostic procedures and solutions for common mechanical and electrical issues.
Tune Up Procedures:
Instructions for carburetor tuning, ignition timing adjustment, and general engine performance optimization.
Electrical Diagnostics:
Detailed guidance for diagnosing and repairing electrical faults using wiring diagrams.
Kickstarter Operation And Repair:
Detailed instructions on the operation and maintenance of the kickstart mechanism, including its engagement and potential repair.
Exhaust System Maintenance:
Information on exhaust pipe removal, installation, and replacement, along with muffler servicing.
Wheel And Tire Service:
Instructions for wheel bearing maintenance, tire removal and installation, and rim care.
Depth:
Complete factory-level repair information, suitable for both novice DIY enthusiasts and experienced professional mechanics. Covers from basic maintenance to full engine and transmission rebuilds.
Troubleshooting Methodology:
The manual employs a systematic troubleshooting approach, combining symptom identification with detailed diagnostic steps, often referencing specific sections and wiring diagrams.
Illustration Quality:
Hundreds of photos and illustrations are included, with enlarged insets to detail specific parts and procedures, enhancing clarity for complex tasks.
Engine Type:
Air-cooled, 45-degree V-twin, OHV (Overhead Valve)
Engine Family:
Shovelhead
Displacement:
74 cubic inches (1200 cc)
Bore X Stroke:
3.4375 in. x 4.25 in. (87.3 mm x 108 mm) - Typical for 74ci Shovelhead
Compression Ratio:
Approx. 8.0:1 (Varies slightly by specific engine build)
Valve Train:
Pushrod activated overhead valves
Horsepower Estimate:
Approx. 60-65 hp at 5800 RPM (Estimated, factory figures vary)
Torque Estimate:
Approx. 65-70 lb-ft at 3500 RPM (Estimated)
Carburetor:
Typically a Keihin butterfly (e.g., 36mm) or Linkert carburetor depending on origin and specifications.
Fuel Type:
Unleaded gasoline, 91 octane (or higher if available)
Oil Capacity:
Approx. 3 quarts (2.8 liters) - Check manual for exact capacity and type.
Oil Type:
Harley-Davidson recommends specific oil formulations, often a straight-weight or multi-grade oil suitable for air-cooled V-twins. SAE 20W-50 or SAE 50 is common for older models.
Oil Change:
Typically every 2,000-3,000 miles or annually, whichever comes first.
Primary Chain Adjustment:
Regular checks and adjustments are critical, often recommended at every oil change or every few thousand miles.
Tune Up Schedule:
Recommended annually or every 5,000-10,000 miles, including spark plug replacement, ignition timing check, and carburetor adjustment.
Engine Oil:
Refer to manual for specific viscosity and type. SAE 20W-50 is a common recommendation for air-cooled V-twins of this era.
Transmission Oil:
Consult the manual for the correct Harley-Davidson transmission fluid or equivalent high-quality alternative.
Primary Chain Case Oil:
Often uses engine oil or a specific primary lubricant. Check manual for correct fluid and capacity.
Common Problems:
Shovelhead engines are known for oil leaks due to their vintage design and materials. Valve train noise, primary chain wear, and carburetor tuning can be ongoing maintenance points. Electrical systems of this era can be prone to wear and require careful inspection.
Heritage:
Harley-Davidson, founded in 1903, is an iconic American motorcycle manufacturer with a rich history of producing powerful, distinctive motorcycles, synonymous with freedom and the open road.
Fxs Evolution:
The FX series, introduced in 1971, was Harley-Davidson's answer to the growing demand for lighter, more nimble motorcycles than their traditional FL Big Twins. The FXS, or Super Glide, was the original FX model, featuring the Shovelhead engine in the lighter frame, often with a sporty front end and distinctive 'boat tail' fender design in its early years. The 1978 model represents a refinement of this successful formula.
Shovehead Production Years:
1966-1984
