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Harley-davidson

Harley Davidson Knucklehead Flathead 1940-1947 Motorcylce Repair Workshop Manual

Harley Davidson Knucklehead Flathead 1940-1947 Motorcylce Repair Workshop Manual

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Vehicle data plateRef 468353
Brand
Harley-davidson
Vehicle
Motorcycle
Models covered
Engines, Flathead, Harley Davidson, Knucklehead
Years
1940, 1941, 1942, 1943, 1944, 1945, 1946, 1947
Format
PDF, searchable, print-ready
Delivery
Instant download after checkout
Language
English

What happens after you pay

  • Download link opens on the order page immediately
  • The same link is emailed to you โ€” re-download any time
  • Open on phone, tablet or PC; print only the pages you need
  • Not sure it covers your model year? Ask us before you buy
๐Ÿท๏ธ Basic Information
Identification
Make:
Harley-Davidson
Model:
Knucklehead Flathead
Model Variant:
EL (61 cu in), FL (74 cu in)
Production Years Covered:
1940, 1941, 1942, 1943, 1944, 1945, 1946, 1947
Codes
Engine Designation:
E-Series (61 cu in), F-Series (74 cu in)
๐Ÿ‘‹ Introduction
Market Position
Target Audience:
Harley-Davidson Knucklehead owners, restorers, mechanics, and vintage motorcycle enthusiasts.
Competitive Analysis
Value Proposition:
Provides dealership-level repair and maintenance information essential for preserving and operating iconic vintage Harley-Davidson motorcycles.
Key Features
Digital Delivery:
Instant download, eliminating shipping delays and physical wear and tear on paper manuals.
Versatility:
Ability to print specific sections as needed for workshop use, or print entire manuals for binder organization.
๐Ÿ“‹ Manual Details
Coverage Areas
Primary Coverage:
Mechanical and electrical repair, maintenance, and troubleshooting
Secondary Coverage:
Specifications, adjustments, and diagnostic procedures
Page Count
Estimated Page Count:
Varies significantly by specific year and model variant, often exceeding 500 pages for comprehensive coverage.
Manual Type
Manual Type:
Workshop Repair Manual / Service Manual
Language
Language:
English
Format
Digital Format:
Adobe Acrobat PDF
๐Ÿ“– Manual Coverage
Systems Covered
Engine Systems:
Engine assembly/disassembly, cylinder heads, cylinders, pistons, connecting rods, crankshaft, camshaft, valvetrain, lubrication system (oil pump, oil lines), cooling (air-cooled), ignition system (magneto, spark plugs).
Transmission Systems:
4-speed constant mesh transmission (primary drive and gearbox), clutch operation and adjustment, gear shifting mechanisms, transmission lubrication.
Chassis Systems:
Frame construction and repair, front fork (Girdraulic or Springer depending on specific year), rear suspension (rigid or early plunger), wheel bearings, steering head bearings.
Electrical Systems:
Lighting (headlight, taillight, brake light), battery, generator/charging system, wiring diagrams, switches, horn.
Braking Systems:
Front and rear drum brake mechanisms, brake shoe adjustment and replacement, brake linkage.
Fuel And Carburetion:
Fuel tank, fuel lines, fuel filter, carburetor (e.g., Linkert M series), throttle controls.
Lubrication And Fluids:
Engine oil specifications, transmission oil, primary chaincase oil, lubrication points, oil change procedures.
Bodywork And Controls:
Seat mounting, handlebar controls, fenders, exhaust system, kickstand.
Procedures Included
Maintenance Procedures:
Routine servicing, oil changes, filter replacements, chain lubrication and adjustment, spark plug inspection, battery maintenance, brake adjustments, clutch adjustments.
Diagnostic Procedures:
Troubleshooting common engine, transmission, and electrical issues, performance checks, identifying wear and tear.
Repair Procedures:
Complete engine overhauls, transmission rebuilds, fork servicing, brake system repairs, electrical component replacement.
Adjustment Procedures:
Ignition timing, carburetor settings, clutch engagement, throttle cable tension, brake linkage.
Technical Depth
Depth Of Information:
Comprehensive, covering detailed disassembly, assembly, repair, and tuning for all major mechanical and electrical components. Suitable for experienced mechanics and dedicated restorers.
๐Ÿ“Š Manual Specifications
File Format
File Format:
Adobe Acrobat PDF
Compatibility:
PC and Mac compatible
Print Quality
Print Quality Recommendation:
Printable sections or full manuals; digital format allows for easy printing of specific procedures without soiling original documentation.
Binding Type
Binding Type Digital:
N/A (Digital Download)
Paper Type
Paper Type Digital:
N/A (Digital Download)
โš™๏ธ Engine Specifications
Primary Engine
Engine Type:
Overhead Valve (OHV) V-Twin
Engine Displacement El:
61 cubic inches (1000 cc)
Engine Displacement Fl:
74 cubic inches (1200 cc)
Bore X Stroke El:
3.00 in x 3.50 in (76.2 mm x 88.9 mm)
Bore X Stroke Fl:
3.4375 in x 4.00 in (87.3 mm x 101.6 mm)
Compression Ratio:
Approximately 6.0:1 to 7.0:1 (depending on year and specific variant)
Performance
Horsepower El:
Approximately 30-35 HP @ 4800 RPM
Horsepower Fl:
Approximately 35-40 HP @ 4500 RPM
Torque:
Significant torque for its era, specific figures vary by year and tuning.
Fuel System
Carburetor Type:
Linkert M-series (e.g., M74, M76, M88)
Fuel Type:
Leaded gasoline (historically), modern equivalent with appropriate octane rating recommended.
๐Ÿ”ง Transmission
Standard
Transmission Type:
4-speed manual, constant mesh
Primary Drive:
Duplex chain within a primary chaincase
Clutch Type:
Dry multi-plate
Features
Gear Selection:
Hand shift lever with foot clutch (early models), foot shift with hand clutch (later models).
๐Ÿ“ Dimensions
Exterior
Wheelbase:
Approximately 56.5 inches (1435 mm)
Weights
Dry Weight El:
Approximately 500-550 lbs (227-250 kg)
Dry Weight Fl:
Approximately 550-600 lbs (250-272 kg)
๐Ÿ›ก๏ธ Safety Features
Ratings
Safety Features Era:
Basic by modern standards; focus on mechanical reliability and rider skill. Drum brakes were standard.
Active Features
Active Safety:
Effective braking system for the period, stable chassis geometry.
Passive Features
Passive Safety:
Robust frame construction.
๐Ÿ’ก Technology Features
Infotainment
Infotainment Features:
N/A (No modern infotainment systems applicable)
Driver Assistance
Driver Assistance Features:
N/A (No modern driver assistance systems applicable)
Connectivity
Connectivity Features:
N/A (No modern connectivity features applicable)
๐Ÿ”ง Maintenance
Service Intervals
Oil Change Interval:
Typically every 1,000-2,000 miles or seasonally, depending on usage and oil type. Consult manual for specific recommendations.
Transmission Service Interval:
Refer to manual; generally involves checking and topping up oil, and periodic drain and refill (e.g., every 5,000-10,000 miles).
Ignition Timing Check:
Periodically, especially if engine performance degrades.
Fluid Specifications
Engine Oil Type:
High-quality motorcycle-specific oil, typically SAE 50 or 60 for this era. Refer to manual for precise grade. Many owners use modern mineral oils with ZDDP additive for older flathead and OHV engines.
Transmission Oil Type:
Gear oil or transmission fluid; specific viscosity and type detailed in manual.
Primary Chaincase Oil:
Dedicated primary chaincase lubricant or engine oil; consult manual for exact specification.
Known Issues
Oil Leaks:
Common due to age and material degradation of seals and gaskets. Manual provides procedures for sealing.
Carburetor Tuning:
Linkert carburetors can require frequent adjustment and maintenance for optimal performance. Manual details tuning procedures.
Valve Adjustment:
Requires periodic adjustment for proper engine operation and longevity.
Electrical Component Reliability:
Older wiring and components may require inspection and refurbishment.
๐Ÿ“š Vehicle History
Brand Heritage
Harley-Davidson Legacy:
The Knucklehead represents a significant era of innovation and design for Harley-Davidson, setting a benchmark for V-twin performance and styling.
Model Evolution
Knucklehead Development:
Evolved from the earlier EL and UL models, incorporating significant improvements in engine design, lubrication, and frame geometry. The 'Knucklehead' moniker comes from the distinctive rocker box covers.
Production
Manufacturing Location:
Milwaukee, Wisconsin, USA
Wartime Production:
Production continued through WWII, with some models potentially adapted for military use or facing material shortages.
๐Ÿ† Awards & Recognition
Recognitions
Historical Significance:
The Knucklehead is universally recognized as a landmark motorcycle and a highly desirable collector's item.

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Check the model year and engine before you buy

Manufacturers change procedures, wiring and part numbers between model years and engine options. If your VIN plate shows a year or engine code that is not listed on the data plate above, contact us with the model, year and VIN and we will confirm coverage before you order.

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