Market Position:
Essential reference for owners and mechanics of the iconic 1968 Harley-Davidson Duo Glide, a pivotal model in the brand's cruiser history, catering to enthusiasts and professional restorers alike.
Competitive Analysis:
This factory manual offers unparalleled accuracy and detail compared to aftermarket guides, providing OEM-specific procedures and specifications crucial for maintaining the authenticity and performance of a vintage Harley-Davidson.
Key Features:
Authoritative OEM information, step-by-step repair instructions, detailed diagrams and illustrations, comprehensive troubleshooting, and exact technical specifications for the 1968 Duo Glide.
Systems Covered:
Engine, Transmission, Clutch, Primary Drive, Fuel System, Ignition System, Electrical System (including lighting, charging, starting), Suspension (front and rear), Brakes (front and rear drum), Chassis, Frame, Bodywork, Wheels, Tires, Handlebars, Controls, and Accessories.
Procedures Included:
Routine maintenance, tune-ups, disassembly, assembly, repair, adjustment, troubleshooting, diagnostics, component replacement, wiring diagrams, specifications, torque values, and overhaul procedures.
Technical Depth:
Comprehensive, covering everything from basic adjustments and fluid changes to full engine and transmission rebuilds. Detailed diagnostic flowcharts and exploded views for intricate procedures.
Electrical System Coverage:
Detailed wiring diagrams, component identification, testing procedures for generator, regulator, starter, ignition coil, lighting circuits, and horn.
Suspension Coverage:
Front fork (Telescopic) overhaul and adjustment, rear shock absorber inspection and replacement, lubrication points.
Brake Coverage:
Front and rear drum brake system inspection, adjustment, shoe replacement, and linkage lubrication.
Bodywork Coverage:
Fender removal and installation, fuel tank mounting and removal, seat assembly, fairing (if equipped) service.
File Format:
N/A (Printed Manual)
Print Quality:
Original factory print quality (typically black and white diagrams, clear text).
Binding Type:
Original factory binding (likely stitched or glued paperback).
Paper Type:
Standard paper stock for workshop manuals of the era.
Accuracy Level:
Factory original specifications and procedures, considered the highest level of accuracy.
Engine Type:
Air-cooled, OHV, V-twin (Panhead)
Displacement:
997cc (61 cubic inches) or 1033cc (63 cubic inches)
Bore X Stroke 61Ci:
3-7/16 in. x 3-9/16 in. (87.31 mm x 90.49 mm)
Bore X Stroke 63Ci:
3-7/16 in. x 3-7/8 in. (87.31 mm x 98.43 mm)
Compression Ratio:
Approx. 7.0:1 to 8.0:1 (varies by specific model and tune)
Horsepower Estimate:
Approx. 50-55 HP @ 5000 RPM (est.)
Torque Estimate:
Approx. 65-70 ft-lbs @ 3500 RPM (est.)
Valve Arrangement:
Overhead Valve (OHV), pushrod-actuated
Cooling System:
Air-cooled
Carburetor Type:
Linkert M74 (or equivalent Zenith/S&S for some variants)
Fuel Type:
Leaded gasoline (appropriate octane rating as per original specifications)
Fuel Capacity:
4.5 US Gallons (17 Liters)
Transmission Type:
4-speed Constant Mesh, Foot Shift, Hand Clutch
Clutch Type:
Dry multi-plate
Transmission Features:
Includes detailed procedures for clutch adjustment, gear selection troubleshooting, and internal transmission component service.
Transmission Fluid Type:
Harley-Davidson Original Equipment Specification (often SAE 50 or SAE 60 gear oil, consult manual for exact spec)
Wheelbase:
Approx. 59.5 inches (1511 mm)
Overall Length:
Approx. 89 inches (2260 mm)
Dry Weight:
Approx. 500-550 lbs (227-250 kg) depending on model variant (FL vs. FLH)
Gross Vehicle Weight Rating:
Not officially specified in the same manner as modern vehicles, but generally understood to be around 750-800 lbs (340-363 kg) for safe operation.
Front Tire Size:
Typically 3.50-19 or similar
Rear Tire Size:
Typically 4.00-18 or similar
Wheel Type:
Spoked wheels
Wheel Bolt Pattern:
N/A (Hub-mounted, not bolt-on wheels in the modern sense)
Infotainment Features:
N/A (Focus on mechanical operation, no electronic infotainment systems).
Driver Assistance Features:
N/A (No electronic driver assistance features).
Connectivity Features:
N/A (No electronic connectivity features).
Engine Oil Change Interval:
Every 1,000 - 2,000 miles or annually (recommendation based on vintage service practices)
Primary Chain Adjustment Interval:
Every 500 - 1,000 miles
Spark Plug Replacement:
As needed, or at major tune-ups (refer to manual for gap and type)
Clutch Adjustment Interval:
Every 1,000 - 2,000 miles
Engine Oil Type:
Harley-Davidson Genuine V-Twin Oil SAE 50 or SAE 60 (or equivalent high-zinc content oil suitable for vintage flat tappet engines)
Engine Oil Capacity:
Approx. 3 quarts (2.8 Liters)
Transmission Fluid Capacity:
Approx. 1 quart (0.95 Liters)
Brake Fluid Type:
Not applicable (uses brake fluid reservoir with internal master cylinder)
Fork Oil Type:
Harley-Davidson Fork Oil (SAE 10W or equivalent)
Fork Oil Capacity:
Specify capacity per leg (refer to manual)
Common Issues:
Oil leaks (rocker boxes, pushrod tubes, crank seals), valve seat wear, carburetor tuning difficulties (Linkert), electrical system reliability (aging wiring), clutch drag, kick-start mechanism wear.
Carburetor Tuning Notes:
Linkert carburetors require precise adjustment of jetting and air screw for optimal performance and starting.
Ignition System Notes:
Battery ignition system (points, condenser, coil) requires regular inspection and adjustment.
Brand Heritage:
Harley-Davidson, founded in 1903, is an iconic American motorcycle manufacturer renowned for its cruiser and touring motorcycles, embodying freedom and the open road.
Model Evolution:
The Duo Glide (FL designation) evolved from earlier Hydra-Glide and Servi-Car models. The 1968 model represents a mature iteration of the Panhead engine era, just prior to the introduction of the Shovelhead engine in 1966 (though some 1966-1969 models still featured the Panhead or a transitional engine). The Duo Glide name itself referred to the introduction of the swingarm rear suspension, a significant upgrade from earlier rigid frames.
Production Years Panhead:
1948-1965 (though transitional models and parts might extend this)
Production Years Duo Glide Era:
Approx. 1958-1964 (with 'Duo Glide' nomenclature specifically for swingarm models prior to the Electra Glide name change).
Manufacturing Location:
Milwaukee, Wisconsin, USA
Recognitions:
The 1968 Harley-Davidson Duo Glide is widely recognized as a classic American motorcycle, a collectible item appreciated for its historical significance, iconic styling, and V-twin rumble. It's a staple in motorcycle collections and rallies worldwide.
Collector Value Rating:
High (depending on condition, originality, and model variant)
