Harley-Davidson XA: The Boxer-Engine Motorcycle Few Remember

Bold Detour - Did you know that Harley-Davidson once built a motorcycle powered by a boxer engine? For a brand that has become almost inseparable from the rumble of V-twin cruisers, the idea sounds surprising today. Yet during one of the most challenging periods in modern history, Harley-Davidson briefly stepped away from its traditional formula and created a machine unlike anything else in its lineup.

During World War II, the U.S. Army asked Harley-Davidson to produce a motorcycle as good as BMW's side-valve R71, and here's the result, the Harley-Davidson XA. (Picture from: Trussty)

The story began during World War II, when Harley-Davidson was already supplying motorcycles to the United States Army through the Harley-Davidson WLA. While the WLA served military duties extensively, concerns emerged regarding engine heat, especially in demanding operating conditions. At the same time, military observers were impressed by the capabilities of Germany’s BMW R71, a motorcycle that had proven effective across dramatically different environments, from the freezing landscapes of Eastern Europe to the scorching deserts of North Africa.

Harley-Davidson WLA, another model beside the XA is manufactured as mainstay rides of American GI's during World War II. (Picture from: Trussty)

One of the key reasons behind the BMW’s reputation was its engineering layout. The R71 used a horizontally opposed boxer engine combined with a shaft-drive system. This configuration was valued for its durability, lower operating temperatures, ease of maintenance, and ability to handle a wide range of terrain—qualities that were especially important for military use in active combat zones.

The 1942 Harley-Davidson XA claimed to be able to overcome the heat engine problem on the Harley-Davidson WLA model. (Picture from: ClassicMotorcycle)

Recognizing these advantages, Harley-Davidson carefully examined the technical design of the BMW motorcycle and began developing a comparable machine of its own. The result was the Harley-Davidson XA, introduced in 1942. Although unmistakably American in origin, the XA adopted several concepts that closely mirrored the BMW R71, most notably the boxer engine arrangement and shaft-drive transmission.

Testing the Harley-Davidson XA, that curious 'boxer,' flat-twin, shaft drive motorcycle designed and built for the US Army around 1942. (Picture from: Kits&Coffe in X)

The XA’s design was created with practicality in mind. Its boxer engine positioned the cylinders on opposite sides of the motorcycle, exposing them directly to airflow and helping dissipate heat more efficiently. This engineering choice delivered measurable results. Reports from the period indicated that the XA operated with oil temperatures roughly 56 degrees Celsius lower than those recorded on the V-twin-powered WLA.

The 1942 Harley-Davidson XA had similar features to the BMW R71, namely both using a boxer engine coupled with the shaft drive. (Picture from: GridOto)

Performance was respectable for a military motorcycle of its era. The XA was equipped with a 738 cc boxer engine producing around 23 horsepower. That output allowed the motorcycle to reach a top speed of approximately 104 kilometers per hour, making it capable of handling both transportation and military support duties under a variety of conditions.

With those boxer engine and shaft drive configuration capable make the Harley-Davidson XA run up to a top speed of around 104 kph. (Picture from: BMWDean)

Despite the technical improvements, the XA never became the standard military motorcycle Harley-Davidson had hoped it would be. Production remained limited, with approximately 1,000 units built between 1942 and 1943. In the end, the United States Army chose to continue using the WLA as its primary motorcycle, largely because it was more economical and already established within military logistics and maintenance networks.

Today, the Harley-Davidson XA remains one of the most fascinating chapters in the company’s history. It represents a rare moment when Harley-Davidson looked beyond its traditional engineering philosophy and experimented with ideas inspired by a rival wartime machine. Although its military career was short and many units were eventually sold to civilian riders, the XA stands as a reminder that innovation sometimes emerges from unexpected influences—and that even the most iconic brands can take surprising detours on their journey.

Kept spur your adrenaline on the power of the two-wheeled monster and stay alive with true safety riding. May God will forgive Your sins and so does the cops...... *** [EKA [13102020] | FROM VARIOUS SOURCES | RIDEAPART | CLASSIC MOTORCYCLE | BMW DEAN ]

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The Mars A20: A Unique Icon of Early Motorcycling

Visionary Machine - Seeing the Mars A20 antique motorcycle today feels like stepping into a different rhythm of engineering history, where machines were not just built for function but also carried a bold sense of experimentation. Among the many early European two-wheelers that shaped the foundation of modern motorcycling, the Mars A20 antique motorcycle stands out as a rare glimpse into how far design thinking had already evolved in the early 20th century. Its presence reflects a period when innovation was still raw, yet surprisingly ambitious, especially in Germany’s rapidly growing industrial landscape.

1921 Mars A20 White Mars. (Picture from: Yesterdays.nl)

The story behind the Mars A20 begins long before motorcycles became the company’s focus. In 1873, Paul Reissmann established Mars in Nuremberg, Germany, initially as a manufacturer of iron stoves and furnaces. Over time, the company expanded its expertise into producing mechanical sirens, grinding machines, and even bicycles, gradually building a strong foundation in mechanical engineering. This steady transformation from household heating products to precision machinery set the stage for Mars to eventually step into the automotive world.

1921 Mars A20 White Mars already has a protective wing to avoid the rider's feet and from water splashes. (Picture from: Yesterdays.nl)

By 1903, Mars had already started experimenting with motorcycles and small car construction, marking a significant turning point in its industrial journey. Among its most remarkable creations emerged the Mars A20, also known as the Weiße Mars or “White Mars,” designed in 1920 by engineer Claus Franzenburger. While the white version became the most iconic, the motorcycle was also available in red and green variations, each reflecting a slightly different visual personality but sharing the same engineering spirit that defined Mars’ approach to design during that era.

1921 Mars A20 White Mars uses a Maybach's boxer twin engine that has a capacity of 955 cc.(Picture from: Yesterdays.nl)

Technically, the Mars A20 antique motorcycle was powered by a Maybach boxer twin engine with a displacement of 955 cc, an impressive specification for its time. Despite its relatively modest output—estimated at around 7 horsepower at the wheel and approximately 12 horsepower at the crankshaft—the machine was built with intention and balance rather than brute force. Its pressed steel frame gave it a futuristic silhouette, setting it apart from many contemporaries that still relied on more traditional construction methods, and reinforcing its reputation as a forward-thinking machine.

However, like many ambitious engineering ventures of the early automotive age, Mars faced challenges beyond design and innovation. The economic instability brought by the inflation crisis around 1923 to 1924 placed significant pressure on the company, gradually weakening its financial foundation. Although Mars continued operating for decades afterward, it eventually ceased production in 1958. Today, the Mars A20 antique motorcycle remains a fascinating reminder of an era when engineering companies were still defining what mobility could become, and its legacy continues to resonate with collectors and enthusiasts who appreciate the roots of motorcycle evolution.

Kept spur your adrenaline on the power of two-wheeled monster and stay alive with the true safety riding. God will forgive Your sins.... *** [EKA [30122019] | FROM VARIOUS SOURCES | YESTERDAYS.NL ]

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The Killer: The Custom Motorcycle That Brought History Back to Life

Heritage Reforged - Custom motorcycles often push the limits of creativity, but few creations have attracted as much attention as The Killer, one of the most remarkable custom motorcycles in 2019. Built by Australian-born motorcycle builder Craig Rodsmith of Rodsmith Motorcycles in the United States, this machine stood out thanks to its unusual shape and highly unconventional engineering.

Rodsmith Motorcycle 'The Killer' by Craig Rodsmith for Haas Moto Museum and Sculpture Gallery at The Handbuilt Motorcycle Show 2019. (Picture from: UltimateMotorcycling)

The project began when Bobby Haas, founder of the Dallas-based Haas Moto Museum, discovered old photographs of a rare Art Deco motorcycle developed by German engineers in Munich during the 1930s. Fascinated by the design, he contacted Rodsmith to explore the possibility of bringing a modern version of the concept to life.

The Killer features the integrated amber headlight, bars, and the thin seat are all similarly crafted from aluminum. (Picture from: BikeExif)

The main inspiration was the 1935 Killinger und Freund Motorrad, a motorcycle remembered for its futuristic styling and front-wheel-drive layout. Rather than copying the original exactly, Rodsmith created a functional tribute that preserved its distinctive character while showcasing modern craftsmanship.

Front view of Rodsmith Motorcycle 'The Killer.' (Picture from: BikeExif)

Its most striking feature was the engine arrangement. Instead of sending power to the rear wheel, The Killer used three hand-built 60cc two-stroke engines mounted in a radial configuration inside the 19-inch front wheel, making it one of the most unusual motorcycles ever constructed.

The Killer completed without a central motor, chain, or driveshaft keeps it minimalist and utterly stunning to behold. (Picture from: BikeExif)

The motorcycle’s chassis was also built entirely by hand without the aid of CNC machines or 3D design software. Every detail was carefully crafted to reflect the flowing Art Deco style of the original inspiration, including an integrated amber headlight and a slim aluminum seat.

Rodsmith Motorcycle 'The Killer' was heavily inspired by this German's art-deco styled front-wheeled drive motorcycle called 'Friedenstaube' (Peace Dove) or Killinger und Freund Motorrad. (Picture from: Wind-Water.nl)

To make the front-wheel-drive system work, Rodsmith engineered a centrifugal clutch connected to a sprocket and axle assembly. The setup delivered power smoothly and created a riding experience unlike that of conventional motorcycles..

The Killer has three 60 cc 2-stroke identical engines, in a radial configuration, on its 19-inch front wheel. (Picture from: BikeExif)

Starting the bike required special engineering as well. Since three engines had to run together, Rodsmith developed a custom Bendix drive system that allowed the electric starter to disengage automatically once the engines were operating.

The Killer is a fully functional bike but the project was commissioned mostly as an artwork to be shown off at the museum. (Picture from: Enrg.io)

According to its creators, The Killer is surprisingly easy to ride despite its unusual design. Rodsmith described the sensation as feeling pulled forward by the engine rather than pushed from behind, giving the motorcycle a unique character on the road.

Although fully functional, The Killer was commissioned mainly as a work of art for display at the Haas Moto Museum. Years later, it remains a fascinating blend of history, engineering, and craftsmanship, proving that even a forgotten idea from the 1930s can inspire one of the most extraordinary custom motorcycles of the modern era.

Kept spur your adrenaline on the power of two-wheeled monster and stay alive with the true safety riding. May God will forgive Your sins and so does the cops......

*** [EKA [06102019] | FROM VARIOUS SOURCES | RODSMITH MOTORCYCLE | HAAS MOTO MUSEUM | BIKEEXIF

| ULTIMATE MOTORCYCLING | ENRG.IO]

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The Moto Major 350 and the Postwar Dream of Radical Motorcycle Design

Postwar Reverie - The years following World War II were filled with a strange mix of exhaustion and optimism. Factories that once served military needs began searching for new identities, and engineers were suddenly free to imagine objects meant not for survival, but for living. In that brief, hopeful window, some of the most unconventional machines ever conceived took shape. One of them was the Moto Major 350, a motorcycle born from postwar ambition and creative freedom, and one that still feels remarkably alive in today’s design-driven era.

The vintage-styled 1947 Moto Major 350 prototype still enchanting until today. (Picture from: MotoRiderUniverse)

Unveiled in 1947, the Moto Major 350 immediately stood apart from conventional motorcycles of its time. Designed by Turin-based engineer Salvatore Maiorca, the bike ignored exposed mechanical honesty and instead embraced flowing form. Its silhouette placed it in the same visual conversation as rare experimental machines like the Killinger & Freund from 1938 or Louis Lucien Lepoix’s customized BMW R12, yet the Moto Major carried a personality entirely its own—more organic, more daring, and unmistakably futuristic.

The 1947 Moto Major 350 is voted as the Best of Show Motorcycles at the Concorso Eleganza Villa d’Este in 2018. (Picture from: TheVintagent)

The origins of this motorcycle are closely tied to Aeritalia, an aerospace company based in Turin and a subsidiary of Fiat. Developed inside Aeritalia’s aerodynamic research facilities, the Moto Major was fully funded as an experimental project, reflecting Fiat’s curiosity about entering the two-wheeled market. This was not Fiat’s first flirtation with motorcycles; a decade earlier, it had explored scooter concepts that predated models like Piaggio’s MP5 Paperino. The Moto Major, however, pushed far beyond experimentation and into radical design philosophy.

From every angle, the Moto Major is stunning and compelling. The sole prototype remains in original and unrestored condition.(Picture from: TheVintagent)

What continues to enchant enthusiasts decades later is its bodywork, which feels less engineered and more sculpted. The steel shell wraps almost the entire motorcycle, leaving only the wheels, headlamp, and handlebars visible. Its form has often been compared to marine life, with smooth, cephalopod-like curves and intricate detailing. Even the silencer resembles a flattened fishtail, reinforcing the organic theme while creating a visual balance rarely seen in motorcycles, vintage or modern. 

A cutaway view of the 350 single-cylinder of Moto Major, and showing the steering system, inline single-cylinder motor, shaft drive, and fuel tank under the saddle. (Picture from: TheVintagent)

Beneath the dramatic exterior lies equally unconventional engineering. The Moto Major 350 used a vertically oriented, liquid-cooled twin-cylinder engine, with two radiators discreetly integrated into the fairing and fed by airflow from the front. Controls were partially concealed, with a hand shifter emerging through the bodywork, while the handlebars remained exposed, creating a subtle tension between enclosure and rider connection.

The Moto Major has twin fishtail exhausts hide a secret with only one side is functional, another one is a dummy for aesthetic balance purposes only. (Picture from: TheVintagent)

The exhaust layout added another layer of visual theater. Twin fishtail outlets extended from the rear, even though the 350 cc version technically required only one exhaust pipe. The second was purely decorative, included solely to preserve symmetry. This decision perfectly captured the philosophy behind the Moto Major—engineering logic existed, but it willingly bowed to aesthetics when necessary.

The handlebars move in a slot in the bodywork, between the speedometer and a steering damper knob. (Picture from: TheVintagent)

Perhaps the most advanced idea was hidden within the wheels themselves. The body functioned as a self-supporting monocoque hull, allowing the fairing to sit extremely close to the wheels. Suspension was not placed between the chassis and wheels, but inside the wheels, between the rims and hubs. Maiorca adapted concepts he had previously explored in aircraft design, reviving the almost-forgotten idea of elastic wheels and pushing motorcycle engineering into uncharted territory.

The Moto Major’s in-wheel suspension uses 12 compressed rubber disc per wheel for suspension, to provide a nominal 50cm of travel. (Picture from: TheVintagent)

Despite the excitement it generated—including a planned collaboration with Pirelli and a sensational public appearance at the 1948 Milan Salon—the Moto Major 350 never entered production. Costs, complexity, and shifting priorities quietly ended the dream. Today, the sole surviving example rests with the Hockenheim Museum Archive, preserved rather than restored due to its delicate and irreplaceable components. Its recognition as Best of Show Motorcycle at the 2018 Concorso d’Eleganza Villa d’Este confirmed what many already felt: the Moto Major 350 is not just a relic, but a timeless expression of how bold imagination can outlast the era that created it. 

Kept spur your adrenaline on the power of the two-wheeled monster and stay alive with true safety riding. God will forgive Your sins and so does the cops.... *** [EKA [07032020] | FROM VARIOUS SOURCES | THE VINTAGENT | BIKEEXIF | MOTORIDERSUNIVERSE ]

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Lino Tonti’s Beautiful Italian Scooter Inspired by Marilyn Monroe

Forgotten Glamour - A remarkable vehicle does not always become famous, and some of the most fascinating creations in automotive history spend decades hidden from public memory. During the golden age of scooters in the 1950s and 1960s, countless designs emerged from both established manufacturers and passionate independent builders. Among them was an exceptionally rare Italian scooter known as the Linto Marilina, a machine whose elegance was inspired by one of the most iconic women of the twentieth century, Marilyn Monroe.

The 1954 Linto Marilina while on display in front of Marilyn Monroe's picture at the Salon Moto Légende 2019. (Picture from: CafeRacerClub.org)

BMW Vision K18 Takes BMW Motorrad Design to the Next Level

Sixfold Horizon - At a time when motorcycle design is increasingly defined by efficiency, digital interfaces, and aerodynamic refinement, the arrival of the BMW Vision K18 feels almost like a deliberate interruption to that trend. It is not just another futuristic study shown for attention; instead, it emerges as a bold reminder that mechanical emotion still has a place in modern engineering. Revealed at the prestigious Concorso d’Eleganza Villa d’Este on the shores of Lake Como, this concept from BMW Motorrad immediately shifts focus back to the raw presence of a machine built around one defining idea: the inline-six engine taken to its expressive extreme.

The BMW Vision K18 Concept is not just another futuristic study shown for attention; instead, it emerges as a bold reminder that mechanical emotion still has a place in modern engineering. (Picture from: Motoplanete)

At the heart of the BMW Vision K18 lies a familiar yet reimagined powerhouse — an 1,800 cc inline-six engine architecture that has long been associated with BMW’s touring heritage, particularly models like the K1600 GT and GTL. Traditionally known for smoothness, distance capability, and calm refinement, this engine has rarely been associated with aggression or visual drama. The K18 changes that perception entirely by placing the engine not as a component within the bike, but as the emotional and structural center of the entire design language. Everything radiates outward from it, as if the motorcycle was constructed to celebrate every cylinder rather than simply house them. 

The BMW Vision K18 Concept bodywork combines hand-shaped aluminum panels formed through planishing techniques with forged carbon elements, producing surfaces that feel both industrial and artisanal. (Picture from: ZigWheels)

Visually, the BMW Vision K18 borrows heavily from aviation inspiration, especially the iconic Concorde, resulting in a silhouette that feels stretched, low, and arrow-like. The body flows with a downward, forward-leaning stance that suggests movement even when stationary, almost like a machine caught mid-takeoff. One of the most distinctive engineering choices is the repositioning of the airbox and tank arrangement, allowing the rear section to be flattened and extended. This creates a striking profile where the bike appears to glide forward as a single continuous form rather than a stack of mechanical parts. 

The BMW Vision K18 Concept has a standout feature is a side panel stretching over two meters, formed from a single continuous piece — a feat that highlights the extreme fabrication ambition behind the project. (Picture from: ZigWheels)

What makes the design even more distinctive is the obsessive repetition of the number six throughout its visual identity. Six air intakes channel airflow through individual pathways, six LED headlights define the front signature, and six exhaust outlets complete the rear composition. This “six-by-six” motif is not accidental decoration but a structured design philosophy BMW refers to as “Full Force Forward,” directly referencing the engine’s cylinder count. Whether viewed as symbolic or architectural, it reinforces the idea that every detail is tied back to the mechanical heart of the motorcycle. 

The BMW Vision K18 Concept Six air intakes channel airflow through individual pathways, six LED headlights define the front signature, and six exhaust outlets complete the rear composition. (Picture from: ZigWheels)

The construction of the Vision K18 goes beyond conventional concept design and enters the territory of experimental craftsmanship. Its bodywork combines hand-shaped aluminum panels formed through planishing techniques with forged carbon elements, producing surfaces that feel both industrial and artisanal. A standout feature is a side panel stretching over two meters, formed from a single continuous piece — a feat that highlights the extreme fabrication ambition behind the project. Additional surface treatments, including flame-sprayed metallic finishes, are used to evoke the heat-blued character of Formula 1 exhaust systems, reinforcing the idea of controlled intensity within the design. | UuuCTYZfnBI |

Beyond aesthetics, the BMW Vision K18 also explores functional experimentation, featuring hydraulically adjustable suspension that can alter the bike’s stance and an actively cooled headlight system that emphasizes the visible engineering approach rather than hiding it. Even the intake system is intentionally exposed, turning airflow management into a visual performance element. According to BMW Motorrad leadership, including CEO Markus Flasch, the project reflects a desire to push beyond conventional boundaries and reimagine what an inline-six motorcycle can represent. While it remains a one-off creation with no confirmed production path, its true value lies in how it reframes expectations — showing that even the most established engine platforms can still inspire radical design thinking in the present day.

 

Kept spur your adrenaline on the power of two-wheeled monster and stay alive with the true safety riding. May God will forgive Your sins and so does the cops...... *** [EKA | FROM VARIOUS SOURCES | BMW-MOTORAD | BMWBLOG ]

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