1942 Harley-Davidson XA: The Shaft-Drive Military Opposed Twin

The 1942 Harley-Davidson XA is one of the most mechanically un-Harley motorcycles ever built in Milwaukee: a 45 cubic inch side-valve, horizontally opposed twin with shaft final drive, foot shift, hand clutch, telescopic front fork, and rear plunger suspension. It belongs to Harley-Davidson’s wartime military program, but not to the familiar WLA lineage. The XA was Harley-Davidson’s answer to a very specific U.S. Army interest in the advantages shown by the German BMW R71: low-maintenance shaft drive, cylinders placed in cooling air, and a motorcycle suited to hard service away from paved American roads.

Best Known For: the XA is the rare World War II Harley-Davidson military opposed twin—Milwaukee’s BMW-inspired, shaft-drive Army motorcycle and one of the great technical outliers in Harley-Davidson history.

Quick Facts

The XA is often researched alongside the WLA, Indian 841, and BMW R71, but it is not merely a variation of Harley’s 45-inch V-twin military machine. Its architecture, control layout, suspension, and final drive place it in a separate mechanical category.

For collectors, those facts matter because the XA cannot be judged by ordinary WLA standards. A correct XA is not a 45 flathead with unusual bodywork; it is a purpose-built military opposed twin with a drivetrain, chassis layout, and control philosophy foreign to Harley’s normal production practice of the period.

Why the 1942 Harley-Davidson XA Matters

The XA matters because it captures a short moment when wartime need overruled brand convention. Harley-Davidson had spent decades refining V-twins, side-valve utility machines, and police and military motorcycles with chain drive and rigid rear frames. The XA set much of that aside and adopted the logic of the BMW R71, whose opposed-twin engine and shaft final drive impressed military observers for durability, serviceability, and suitability to difficult terrain.

It also matters because it was not the machine the U.S. Army ultimately standardized around. The Jeep changed the military utility equation, and Harley’s WLA was already a practical, proven, mass-produced motorcycle for dispatch, escort, and general service. The XA became a limited-production experiment rather than a new Harley-Davidson direction, which is precisely why surviving examples attract such focused attention from serious military motorcycle collectors.

Historical Context and Development Background

Harley-Davidson in Wartime Production

By the early 1940s, Harley-Davidson was deeply engaged in military supply. The WLA, derived from the civilian WL 45-inch flathead, became the best-known American military motorcycle of the Second World War. It was rugged, familiar to Harley mechanics, and readily adapted to blackout lighting, heavy carriers, leg shields, skid plates, and other Army requirements.

The XA, however, came from a different brief. The Army had studied European military motorcycles, including the BMW R71, and was interested in a machine that did not depend on exposed chains for final drive. Shaft drive promised reduced maintenance in dust and sand, and the opposed twin placed both cylinders directly in the airflow rather than tucking one behind the other as on a fore-and-aft V-twin.

The BMW R71 Influence

The XA is commonly described as BMW-inspired, and that description is mechanically justified. Its horizontally opposed side-valve twin, shaft drive, foot shift, hand clutch, telescopic fork, and rear plunger suspension all reflect the R71 pattern rather than Harley-Davidson’s established V-twin practice. The XA was not a styling exercise; it was a functional attempt to meet a wartime service requirement with an architecture already proven in European military use.

The Indian 841 emerged from the same general Army interest in shaft-drive motorcycles, though Indian chose a different engine layout. Together, the XA and 841 form a fascinating American wartime side chapter: two major U.S. manufacturers building motorcycles that looked beyond their own traditions because the Army’s operating requirements demanded it.

Engine and Drivetrain

The XA’s engine is a 45 cubic inch side-valve horizontally opposed twin, commonly listed at 738 cc. Unlike Harley’s WL and WLA V-twin, the XA’s cylinders project laterally into the airstream, an arrangement valued for cooling and mechanical balance. The engine is a flathead design, so valve gear is contained low in the cylinder block rather than using overhead valves or pushrod-operated rocker gear.

The drivetrain is where the XA most clearly departs from Milwaukee orthodoxy. The crankshaft and transmission layout feed a shaft final drive rather than a rear chain. A four-speed gearbox, hand clutch, and foot shift gave the XA a control arrangement much closer to European practice than to the hand-shift, foot-clutch Harley military V-twins familiar to WLA riders.

Carburetion and ignition equipment should be verified carefully against XA parts literature on any restoration candidate, as wartime motorcycles were often altered after service. Period and marque references generally describe the XA as using conventional carbureted induction and battery/coil electrical practice rather than the later postwar refinements associated with civilian touring Harleys.

That specification table shows why the XA is prized as a mechanical anomaly. The engine displacement aligns it with Harley’s 45-inch military class, but nearly everything about the way power is delivered to the rear wheel is outside the normal Harley-Davidson pattern of the era.

Chassis, Suspension, and Braking

The XA’s chassis is as important as its engine. A telescopic front fork and rear plunger suspension gave it a very different stance and road behavior from the rigid-rear, spring-fork WLA. On a correct machine, the side profile is immediately recognizable: boxer cylinders protruding from the lower frame, a shaft-drive rear hub, and a suspension layout that looks more European military than American utility V-twin.

Drum brakes front and rear were typical of the period. The braking system should not be judged against postwar hydraulic or modern standards; it was designed for military speeds, unpaved roads, and a machine carrying equipment rather than for sport riding. The suspension, however, was advanced within the Harley-Davidson context, particularly because production Harleys would not receive the famous Hydra-Glide telescopic fork until after the war.

The XA’s visual identity is not subtle. A WLA looks like a militarized Harley 45; an XA looks like a military flat twin from a parallel design universe, with Harley-Davidson cast into the story rather than immediately written across every mechanical decision.

Riding Experience and Mechanical Character

Starting an XA is a period ritual: fuel on, ignition set, carburetion prepared, and a deliberate swing on the kick starter rather than the casual jab expected of later motorcycles. Once running, the horizontally opposed twin gives a different rhythm from a Harley V-twin. The engine pulse is broad and mechanical, but the opposing cylinders reduce the fore-and-aft rocking associated with a narrow-angle V-twin.

The hand clutch and foot shift are central to the experience. A rider accustomed to a WLA’s foot clutch and tank shift would immediately notice the XA’s more European control logic. Gear changes are less theatrical than on the hand-shift Harleys, though still very much a 1940s military motorcycle exercise: deliberate movement, mechanical engagement, and no expectation of modern synchromesh softness.

On roads of its era, the XA would have felt planted and serviceable rather than sporting. Shaft drive removed chain lash and exposed-chain maintenance from the rider’s list of concerns, while the plunger rear suspension gave a degree of compliance absent from rigid Harleys. The brakes demand anticipation, especially with military equipment aboard, and low-speed maneuvering asks the rider to remember the width of the projecting cylinders.

Identification and Originality

What Makes an XA an XA

The core identifying features are the XA model code, the side-valve horizontally opposed twin engine, shaft final drive, telescopic fork, rear plunger suspension, and military configuration. A genuine XA should not be confused with a WLA, WL, or postwar civilian Harley modified with military paint. The engine architecture alone separates it from every production Harley-Davidson V-twin of the period.

Collectors should treat engine and frame numbering with care. Because the XA was produced in limited numbers and many military motorcycles passed through depots, surplus channels, civilian hands, and later restorations, documentation is crucial. Avoid relying on casual number-decoding claims unless they are supported by factory records, recognized marque references, or authoritative military motorcycle scholarship.

Correct Equipment and Common Restoration Traps

Surviving XAs often require close inspection for swapped or improvised parts. Controls, lighting, saddles, instruments, fasteners, fenders, luggage hardware, and military fittings may have been replaced with WLA, civilian Harley, reproduction, or non-Harley components over decades of service and collecting. The shaft-drive rear assembly, plunger suspension pieces, and XA-specific engine castings are especially important because they define the motorcycle mechanically and are not casual cosmetic details.

Finish is another major originality issue. The correct visual language is wartime military utility, not polished civilian restoration. Olive-drab paint, blackout equipment where applicable, subdued hardware, and correct service fittings matter more to serious collectors than decorative chrome or over-restored presentation.

Model Code and Variant Breakdown

The XA was not a broad civilian family with annual trim ladders. It was a tightly focused military model. The table below places the XA beside the most relevant Harley-Davidson military code that enthusiasts often compare with it.

The WLA is included because it is the common point of confusion in the collector marketplace. It is not an XA variant. It is the standard wartime Harley 45, while the XA is the rare opposed-twin shaft-drive branch that did not become Harley’s military production mainstay.

Performance and Dimensional Specifications

Commonly cited XA references list approximately 23 horsepower and a maximum speed in the region of 65 mph. Those figures should be understood as period military and factory-style specification figures rather than modern road-test data. Acceleration times, quarter-mile results, and comparable performance numbers are not consistently documented in reliable period sources and should not be invented for buying or restoration research.

The more meaningful performance point is operational rather than sporting. The XA was intended to reduce maintenance demands and improve service suitability in adverse conditions. Its value lay in cooling, shaft-drive cleanliness, and durability logic, not in outperforming civilian roadsters.

Compared With Related Models

Harley-Davidson XA vs. WLA

The WLA is the motorcycle most people picture when they hear “World War II Harley.” It is a militarized 45-inch V-twin with chain final drive, rigid rear frame, spring fork, foot clutch, and hand shift. The XA shares the same general displacement class but almost nothing of the WLA’s basic mechanical layout.

For a buyer, the WLA is easier to understand, easier to source parts for, and more commonly restored. The XA is rarer, more technically unusual, and less forgiving of missing components. A WLA can be restored from a broader ecosystem of parts; an XA demands deeper specialist knowledge.

Harley-Davidson XA vs. Indian 841

The Indian 841 is the natural American comparison because it was another wartime shaft-drive military motorcycle built in response to similar Army thinking. The Indian used its own engineering solution rather than simply following Harley’s V-twin pattern. Both machines illustrate how seriously the Army considered shaft drive and European-style military motorcycle layouts before the Jeep absorbed much of the role motorcycles had been expected to fill.

Harley-Davidson XA vs. BMW R71

The BMW R71 is the design shadow behind the XA. The comparison is unavoidable: side-valve opposed twin, shaft drive, plunger rear suspension, and military service logic. The XA’s collector appeal partly rests on that transatlantic engineering connection, especially because Harley-Davidson so rarely built anything outside its V-twin identity.

Restoration and Ownership Notes

Restoring an XA is not like restoring a WLA with a more interesting story. The rare and model-specific pieces determine the project. Engine castings, gearbox components, shaft-drive parts, rear-drive assemblies, plunger suspension hardware, and XA-specific frame and mounting details are all far more consequential than cosmetic military accessories.

Mechanical rebuilding requires a restorer who understands side-valve clearances, period lubrication systems, shaft-drive alignment, and the scarcity of correct replacement parts. Reproduction support exists for some military Harley-Davidson components, but the XA’s limited production means the parts situation is narrower and more specialist-dependent than for the WLA.

Documentation has a direct effect on confidence. A convincing XA should have coherent numbers, correct major assemblies, and a restoration file that explains what has been repaired, replaced, or reproduced. With a motorcycle this rare, an attractive olive-drab finish can conceal a great deal of missing originality.

Buyer and Restoration Inspection Points

A serious XA inspection should start with the items that cannot be easily found later. Cosmetic military fittings are important, but they are not where the financial and historical risk usually sits.

The best XA purchases are usually the ones with boring paperwork and exciting hardware: correct major assemblies, known provenance, and a restoration history that does not require the buyer to take the seller’s word for every hard-to-see detail.

Collector and Market Relevance

The XA occupies a narrow but serious collector niche. It appeals to Harley-Davidson collectors because it is so unlike the rest of the marque’s production history, to military motorcycle collectors because it represents a rare U.S. Army experiment, and to engineering-minded enthusiasts because it connects Milwaukee to the BMW R71 school of military motorcycle design.

Rarity is central to its desirability, but rarity alone is not the whole story. The XA is desirable because the mechanical differences are real: shaft drive, opposed twin, foot shift, hand clutch, telescopic fork, and rear plunger suspension. These are not trim variations. They are the reasons the motorcycle exists.

Collectors typically value correct, documented, substantially complete machines with XA-specific components intact. Incomplete projects can be deeply challenging because the pool of correct parts is small. Auction interest tends to follow authenticity, provenance, and restoration quality rather than mere military paint.

Cultural Relevance

The XA did not become the face of the American motorcycle at war; the WLA filled that role in photographs, museums, reenactment circles, and popular memory. That relative obscurity gives the XA a different cultural position. It is the machine for the enthusiast who already knows the standard story and wants the chapter where Harley-Davidson briefly stepped outside its own grammar.

Its military relevance is tied to experimentation rather than mass deployment. The XA shows how battlefield requirements, European influence, and American manufacturing capacity intersected during the Second World War. It also demonstrates that Harley-Davidson’s conservatism was never absolute; when a government contract pointed toward shaft drive and an opposed twin, Milwaukee built one.

FAQs

What years was the Harley-Davidson XA produced?

The XA is associated with 1942 wartime production. Exact production totals are not uniformly stated in all sources, but approximately 1,000 machines were built, with 1,011 commonly cited in Harley-Davidson and military motorcycle references.

What engine does the 1942 Harley-Davidson XA use?

The XA uses a 45 cubic inch, approximately 738 cc, side-valve horizontally opposed twin-cylinder engine. It is a flathead opposed twin, not a Harley 45-degree V-twin like the WLA.

Was the Harley-Davidson XA shaft drive?

Yes. Shaft final drive is one of the defining features of the XA and one of the principal reasons the motorcycle was developed for military evaluation. It distinguished the XA sharply from Harley’s chain-drive WLA.

Is the XA the same as a Harley-Davidson WLA?

No. The WLA is a militarized 45-inch V-twin with chain drive, hand shift, foot clutch, and conventional Harley military architecture. The XA is a 45-inch opposed twin with shaft drive, foot shift, hand clutch, telescopic fork, and rear plunger suspension.

Why did Harley-Davidson build a BMW-style motorcycle?

The U.S. Army had observed the advantages of European shaft-drive opposed-twin military motorcycles, particularly the BMW R71. Harley-Davidson developed the XA to satisfy that military interest, emphasizing cooling, reduced final-drive maintenance, and suitability for difficult service conditions.

Are Harley-Davidson XA parts easy to find?

No. General military Harley-Davidson parts are easier to source for the WLA than for the XA. XA-specific engine, shaft-drive, suspension, frame, and control components are scarce, which makes complete and well-documented motorcycles much more attractive to collectors and restorers.

What makes a 1942 Harley-Davidson XA collectible?

The XA combines low production, wartime military purpose, BMW-influenced engineering, shaft drive, opposed-twin architecture, and a control layout unusual for Harley-Davidson. Its collectibility comes from being both historically significant and mechanically separate from mainstream Harley production.

Collector Takeaway

The 1942 Harley-Davidson XA is important because it proves Harley-Davidson was capable of abandoning its own habits when the assignment demanded it. Milwaukee did not merely repaint a 45 for military use; it built a shaft-drive opposed twin with suspension and controls that belonged to a different engineering tradition.

For the collector, that makes the XA more than a rare wartime Harley. It is the exception that explains the rule: a motorcycle built at the intersection of Army requirements, BMW influence, and American manufacturing, then left as a fascinating dead end when military priorities changed. A correct XA is one of the most intellectually satisfying Harley-Davidsons to study because every major component tells you why it was made—and why nothing quite like it followed.