Positioning:
The Harley-Davidson FXS represents the custom cruiser segment of the late 1970s, offering a blend of classic styling and robust V-twin performance, often associated with the 'Low Rider' aesthetic. This manual targets owners and independent mechanics seeking to maintain or restore these iconic machines.
Competitors:
Competed with other American V-twin cruisers and custom motorcycles of the era. The FXS offered a more relaxed riding position and often a different wheelbase configuration compared to the FLH models.
Vehicle Attributes:
Shovelhead engine, distinctive styling, custom riding position, typically featuring extended front ends and ape hanger handlebars on certain configurations. Known for its torque and distinctive exhaust note.
Engine Systems:
Engine overhaul, cylinder head, cylinder block, pistons, crankshaft, connecting rods, camshaft, valve train, oil pump, primary drive, clutch, transmission assembly (4-speed), carburetor (e.g., Keihin CV or Linkert variations), ignition system (points ignition, early electronic options), exhaust system.
Chassis Systems:
Frame, front forks (e.g., leading axle, glide type), rear suspension, wheels, tires, brakes (front and rear drum or early disc), steering, primary chain case, drivetrain.
Electrical Systems:
Wiring diagrams, battery, charging system (generator or alternator), lighting, ignition switches, starter motor, horn, instrumentation, accessory wiring.
Maintenance Procedures:
Routine maintenance checks, lubrication, filter replacement (oil, air), spark plug service, chain adjustment, brake adjustment, battery care, tire pressure checks.
Repair Procedures:
Engine disassembly and reassembly, transmission rebuild, brake system repair, electrical system troubleshooting and repair, carburetor tuning and rebuild, fork service, suspension overhaul, frame inspection and repair.
Troubleshooting:
Diagnostic charts, symptom-based troubleshooting guides for engine, electrical, and mechanical issues.
Depth Of Information:
Comprehensive. Covers everything from basic adjustments and fluid changes to complete engine and transmission overhauls, including detailed torque specifications, clearances, and special tool requirements.
Engine Type:
Air-cooled, 45-degree V-twin
Engine Displacement:
73.7 cu in (1200 cc)
Bore X Stroke:
3.4375 in x 4.25 in (87.3 mm x 108 mm) - approximate, may vary slightly by specific build.
Horsepower:
Approximately 60-65 hp (at crankshaft), actual figures vary based on tuning and specific configuration.
Torque:
Approximate torque figures were around 65-70 ft-lbs at ~3500 RPM, emphasizing low-end grunt.
Carburetor:
Typically a Keihin Butterfly carburetor (e.g., 36mm or similar), though some earlier or custom models might retain Linkert variants. Some later production might have seen the introduction of the CV carb.
Fuel Type:
Unleaded gasoline, 87 octane or higher recommended.
Ignition Type:
Battery and coil ignition with points and condenser, or early electronic ignition systems.
Crash Test Ratings:
N/A - Motorcycle safety testing protocols and ratings were not standardized or widely published in this manner for motorcycles of this era.
Braking System:
Front: Disc brake (caliper and rotor). Rear: Drum brake. Manual covers inspection, adjustment, and replacement procedures.
Frame Construction:
Steel tube frame construction.
Infotainment Features:
N/A - This era of motorcycles focused on core mechanical and electrical systems, not electronic infotainment. Instrumentation typically included speedometer, tachometer (optional), oil pressure light, and neutral indicator.
Driver Assistance Systems:
N/A - No electronic driver assistance systems were available on motorcycles of this vintage.
Connectivity Options:
N/A - No electronic connectivity features.
Oil Change Interval:
Typically every 2,000-3,000 miles or annually, whichever comes first. Consult manual for exact HD specifications.
Spark Plug Replacement:
Recommended every 5,000-10,000 miles, or as needed based on inspection.
Primary Chain Adjustment:
Check and adjust every 5,000 miles or as slack is noted.
Engine Oil Type:
Harley-Davidson recommends SAE 20W-50 or 50W motorcycle oil. Specific HD part numbers like HD-1 were common. Aftermarket equivalents meeting HD specifications are widely used.
Transmission Oil Type:
Harley-Davidson recommends primary drive/transmission lubricant. SAE 80W-90 gear oil or specific Harley-Davidson primary fluids were used.
Brake Fluid Type:
DOT 3 or DOT 4 brake fluid for disc brake systems. Manual will specify.
Shovelhead Common Problems:
Oil leaks (pushrod tubes, rocker boxes, crankcase seals), carburetor tuning difficulties, ignition timing issues, valve guide wear, primary chain tensioner wear, potential for pushrod tube leaks. The manual addresses these with repair procedures.
1979 Specific Concerns:
Early 4-speed transmissions might have specific wear patterns. Ignition systems of this era require regular maintenance. Carburetor jetting can be sensitive to altitude and modifications.
Heritage:
Harley-Davidson has a long and storied history dating back to 1903, synonymous with American motorcycle manufacturing and the V-twin engine.
Shovelhead Era:
The Shovelhead engine, introduced in 1966, replaced the Panhead. It powered Harley-Davidson motorcycles through the 1970s and early 1980s. The FXS model line, particularly the 'Low Rider' variants, emerged in the mid-1970s to cater to the custom and cruiser market.
Production Period:
The Shovelhead engine was produced from 1966 to 1984. The FXS model specifically gained popularity throughout the 1970s.
Manufacturing Location:
Milwaukee, Wisconsin, USA
