Overview of “Motorcycle, Solo (Harley-Davidson Model WLA)” Technical Manual


This technical manual, published by the United States War Department in 1943, provides comprehensive instructions for operating and maintaining the Harley-Davidson Model WLA motorcycle, a crucial piece of military equipment during World War II. The manual is divided into two parts: Part One focuses on vehicle operating instructions, covering everything from pre-starting checks to driving precautions and proper engine starting procedures. Part Two delves into organizational maintenance, outlining the responsibilities of different maintenance echelons within the military and providing detailed instructions for inspecting and servicing various vehicle components.

The manual emphasizes the importance of regular preventive maintenance as a key to ensuring the motorcycle’s reliability and safety. Detailed procedures are outlined for daily, weekly, and more infrequent inspections and services. Throughout the manual, specific instructions are provided for various tasks, including adjusting controls, replacing parts, and troubleshooting common mechanical problems. The manual also includes numerous illustrations to aid in understanding the various components and procedures.

harley davidson wla motorcyle

Facts from the “Motorcycle, Solo (Harley-Davidson Model WLA)” Technical Manual

Here are 20 unique facts from the text:

  1. The Model WLA motorcycle is powered by a V-type, air-cooled gasoline engine. This is stated directly in the description of the vehicle.
  2. The engine operates on the 4-stroke, 4-cycle principle. This is also stated in the description of the vehicle.
  3. The engine is air-cooled, relying on air movement and oil circulation to dissipate heat. This explains how the engine is cooled.
  4. The engine should never be operated for more than 1 minute when the motorcycle is not in motion. This is to prevent overheating of the air-cooled engine.
  5. The motorcycle has a 2-cylinder engine with a bore of 2¾ inches and a stroke of 313/16 inches. This provides specific dimensions of the engine.
  6. The engine displacement is 45.12 cubic inches, and the compression ratio is 5.0:1. This provides information about the engine’s performance characteristics.
  7. The motorcycle has a maximum allowable speed of 65 mph and an average mileage of 35 miles per gallon on hard surfaces. This indicates the motorcycle’s speed and fuel efficiency capabilities.
  8. The cruising range without a fuel refill is 100 miles. This demonstrates the motorcycle’s range for extended operations.
  9. The motorcycle’s fuel capacity is 33/8 U.S. gallons, and its oil tank capacity is 11/8 U.S. gallons. This specifies the motorcycle’s fuel and oil holding capacity.
  10. The transmission capacity is ¾ pint. This gives the amount of transmission fluid required for proper lubrication.
  11. The rear wheel service brake should be in such condition that a medium-hard application will cause the rear wheel to lock. This emphasizes the importance of having a responsive rear brake.
  12. The auxiliary front wheel brake should be applied lightly and cautiously, especially on wet or slippery roads. This advises caution when using the front brake to avoid losing control.
  13. The vehicle should always be operated in the highest gear possible consistent with the tactical situation. This encourages maximizing engine efficiency by minimizing unnecessary strain.
  14. The steering damper is an adjustable friction device to dampen the turning action of the forks and prevent wobble. This explains the function of the steering damper.
  15. A new motorcycle engine should be broken in for at least the first 1,000 to 1,200 miles of service. This highlights the importance of gradual break-in for long-term engine health.
  16. The engine oil tank is located on the right side of the motorcycle, and the fuel tank is on the left side. This clarifies the location of the tanks.
  17. The engine oil should be changed every 1,000 miles, or more frequently under dusty or harsh conditions. This specifies the frequency of oil changes.
  18. The engine oil level should be checked daily and replenished as necessary to maintain a level within 1 inch of the top. This emphasizes the importance of regular oil level checks.
  19. The drive chains are lubricated by engine oil pumps. This explains the lubrication system for the drive chains.
  20. The crankcase breather outlet and rear chain oil feed pipe must be kept clear. This emphasizes the importance of maintaining clear passages for proper engine ventilation and lubrication.

Statistics from the “Motorcycle, Solo (Harley-Davidson Model WLA)” Technical Manual

Here are 20 unique statistics from the text:

  1. 2 cylinders: The motorcycle has a 2-cylinder engine.
  2. 2¾ inches: The cylinder bore of the engine is 2¾ inches.
  3. 3 13/16 inches: The engine stroke is 3 13/16 inches.
  4. 45.12 cubic inches: The engine displacement is 45.12 cubic inches.
  5. 5.0:1: The engine compression ratio is 5.0:1.
  6. 6.05 horsepower: The engine horsepower rating is 6.05.
  7. 65 mph: The maximum allowable speed of the motorcycle is 65 mph.
  8. 35 miles per gallon: The average mileage on hard surfaces is 35 miles per gallon.
  9. 100 miles: The motorcycle’s cruising range without a refill is 100 miles.
  10. 33/8 U.S. gallons: The fuel capacity of the motorcycle is 33/8 U.S. gallons.
  11. 11/8 U.S. gallons: The oil tank capacity of the motorcycle is 11/8 U.S. gallons.
  12. ¾ pint: The transmission capacity is ¾ pint.
  13. 18 pounds: The recommended tire pressure for the front tire is 18 pounds.
  14. 20 pounds: The recommended tire pressure for the rear tire is 20 pounds.
  15. 1,000 miles: Engine oil should be changed every 1,000 miles.
  16. 1 inch: The oil tank should be filled to within 1 inch of the top.
  17. ½ inch: The front chain should have a ½-inch deflection when adjusted correctly.
  18. ½ inch: The rear chain should have a ½-inch deflection when adjusted correctly.
  19. 0.002 inches: The thickness of washers used to adjust chain oilers is 0.002 inches.
  20. 0.022 inches: The correct gap for the circuit breaker points is 0.022 inches.

Terms from the “Motorcycle, Solo (Harley-Davidson Model WLA)” Technical Manual

Here are 10 terms used in the text with definitions:

  1. Air-cooled engine: An engine that relies on the flow of air over the engine components to dissipate heat, rather than a separate cooling system using liquid.
  2. Dry-sump: A lubrication system where the oil is stored in a separate tank, rather than within the engine crankcase.
  3. Circuit breaker: An electrical device that interrupts the flow of current in a circuit when a fault occurs.
  4. Condenser: An electrical component that stores electrical energy temporarily.
  5. Constant-mesh transmission: A transmission where the gears are always in mesh, and shifting occurs by engaging or disengaging clutches that connect the gears to the output shaft.
  6. Shifter clutch: A clutch used in a transmission to engage or disengage gears.
  7. Valve tappet: A small mechanical part that adjusts the clearance between the valve stem and the rocker arm.
  8. Scavenger pump: A pump used in a dry-sump lubrication system to return oil from the engine crankcase to the oil tank.
  9. Breather valve: A valve in the engine crankcase that allows for venting of air and gases to prevent pressure buildup.
  10. Radio bonding: Connecting the metal components of a vehicle together to create a ground path and reduce radio interference.

Examples from the “Motorcycle, Solo (Harley-Davidson Model WLA)” Technical Manual

Here are 10 specific examples used in the text:

  1. Overheating due to idling engine without motion: The manual warns against idling the engine for more than a minute without the vehicle being in motion, as this can lead to overheating.
  2. Clutch slipping due to worn clutch disks: The manual describes how a clutch that slips when engaged is often due to worn clutch disks and recommends replacing them.
  3. Transmission “jumping out of gear” due to shifter clutch wear: The manual explains that if the transmission jumps out of gear even with the shifter linkage adjusted correctly, the shifter clutches are likely worn and need to be serviced.
  4. Engine missing due to water in fuel: The manual details how water in the fuel tank can cause hard starting, spitting, and misfiring. It advises draining and refilling the fuel tank and carburetor bowl to address the issue.
  5. Lean spot in carburetor due to dirt and crust: The manual explains that dirt and crust can build up inside the carburetor, causing a lean spot in the mixture between idling and 30 mph. It recommends replacing the carburetor to resolve the issue.
  6. Overheating due to clogged air cleaner: The manual highlights how an overfilled or excessively dirty air cleaner can restrict airflow to the carburetor, leading to an overrich mixture and overheating. It advises cleaning the air cleaner elements and ensuring proper oil level.
  7. Spark knock due to faulty spark plugs: The manual emphasizes that faulty spark plugs are a common cause of engine misfires, overheating, and spark knock. It recommends replacing the spark plugs with new ones of the correct heat range.
  8. Engine noise due to loose chain: The manual explains how a loose front drive chain can create a noise similar to engine knock, and a loose rear chain can cause jerky operation and rattling noises. It advises adjusting the chains to the correct tension.
  9. Front wheel pulling to one side due to misaligned wheel: The manual describes how a misaligned rear wheel can cause the motorcycle to pull to one side. It advises aligning the rear wheel correctly to address this issue.
  10. Weaving at high speed due to tight steering head bearings: The manual explains that tight steering head bearings can lead to weaving at high speeds. It advises checking and adjusting the steering head bearings if necessary.

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