Je vous partage cet article du magazine anglais Motor Sport, il synthétise l'histoire industrielle de Soichiro Honda pendant la seconde guerre mondiale.

How Honda, Kawasaki, Suzuki and Yamaha were forged by WW2
January 1st 2025
The Japanese manufacturers are having a horrible time in MotoGP, perhaps their toughest since they evolved from manufacturing weaponry for the Japanese military in World War Two.

Japan’s Big Four motorcycle manufacturers – Honda, Kawasaki, Suzuki and Yamaha – ruled bike racing from the 1960s until very recently. More than half a century of racetrack supremacy, along with (and funded by) total domination of the global road-bike market, all the way from step-thru scooters to superbikes.

After World War Two there were as many as two hundred motorcycle manufacturers in Japan, but by the early 1970s the vast majority had gone bust, while others were absorbed. Only Honda, Kawasaki, Suzuki and Yamaha remained.

Why and how did that massive purge take place to create Japan’s so-called Big Four?

The Japanese manufacturers’ association helped create a hugely competitive national racing scene – mostly off-road and often involving riding up volcanoes – which quickly sorted the quick from the dead, laying one of the foundations for the Big Four’s crushing push into world-championship racing.

‘Competition racing to cull the oversized herd of makers operating in the early 1950s was a plan that developed gradually,’ writes historian Jeffrey Alexander in his excellent book Japan’s Motorcycle Wars.

Alexander’s book is an academic publication, as opposed to a commercial publication, so it’s little known, even though it’s been around a while. It offers an incredibly detailed history of the Japanese motorcycle industry, from the earliest days of the last century, supported throughout by in-depth interviews with the engineers and managers that made the grade, as well as those that didn’t.

If the Big Four survived and prospered because they succeeded in national racing, why did they dominate and why did they leave their rivals in the dust when selling road bikes?

Alexander offers historical proof that the main reason these companies got ahead was their role in arming Japan’s army, navy and air force during World War Two and during the country’s imperial ambitions preceding the 1939-1945 conflict, against China, Russia and other countries.

This is not criticism of these companies. Not at all. Most industries are sucked into conflicts whether they like it or not. Indeed the link between Japanese motorcycles and the Japanese military shouldn’t come as a surprise, because many motorcycle brands in many countries have their origins in producing military hardware. Motorcycles are smaller than cars so they are a great way of filling unused production-line space when demand for weapons and munitions slumps.

BMW started out making aircraft engines for the German military during the First World War. Banned from this business by the 1919 Treaty of Versailles, BMW ventured into motorcycles.

BSA – for Birmingham Small Arms – and Royal Enfield started out making firearms for the British military in the late 19th century, then moved into manufacturing bicycles and motorcycles.

Italian brands MV Agusta and Aermacchi started out making military airplanes, but like post-WW1 BMW, they had to shut down these operations according to the WW2 peace treaty. Both switched their factories to motorcycle production.

Czech manufacturer Jawa was founded by famed military inventor and weapons manufacturer František Janeček, who moved into motorcycle production when wartime demand slumped after WW1. He bought the German Wanderer brand, hence Jawa – the first two letters of Janeček and Wanderer.

German brand Zündapp – famed for its two-stroke motorcycles, which won the 1984 80cc riders’ and constructors’ world championships – got its name from the original Zünder und Apparatebau (igniters and apparatus) company, founded during WW1.

Once again, before we get into the detail, I want to underline the fact that telling the story of the rise of Japan’s Big Four from the ashes of post-war Japan is in no way a criticism of these companies.

The significance of Alexander’s research is that while some people know about Soichiro Honda’s beginnings – making piston rings for the Japanese air force in WW2 – and Kawasaki Aircraft Industries’ role in the war, very few know exactly how the conflict put Kawasaki, Honda, Suzuki and Yamaha on the road to global greatness.

After the war the US occupied Japan for almost seven years, during which time the Americans made the rules. The Japanese were banned from creating aircraft and other military hardware, leaving engineers and workers idle and factory space empty.

At the same time, people needed cheap transport to get around the ravaged towns, cities and countryside.

Company management that had spent the war years supplying the Japanese army, navy and air force, needed a way to keep their businesses going and the country moving. Motorcycles were the answer.

Alexander pinpoints the four factors that brought success to the Big Four…

“Each of the Big Four makers’ success involved four crucial components:

Wartime precision manufacturing and management experience.

A resultant understanding of the importance of mass production and die-casting techniques.

Swift development of a product technologically equivalent to European models

A strong financial position – or capacity to secure development capital from government agencies, banks or major firms – for rapid investment in advanced production equipment.”

The Big Four weren’t Japan’s only big automotive names to come out of WW2. Today’s Mitsubishi Motors is a successor of Mitsubishi Heavy Industries, which built the famous WW2 Zero fighter. The Nakajima Aircraft Company, which built fighters, bombers and torpedo bombers, became Fuji Heavy Industries after the war and eventually rebranded as Subaru.

Fuji Heavy Industries engineers had to be resourceful to survive in Japan’s devastated postwar landscape. In 1946 they created the hugely popular Rabbit scooter of which more than half a million were sold. The wheels on early Rabbits were tailwheels salvaged from the Nakajima Ki-84 Hayate, one of Japan’s most effective WW2 fighter planes.

Honda

Honda started selling motorcycles the same year as Fuji, Suzuki followed in 1952, Kawasaki in 1953 and Yamaha in 1954.

Mr Honda had established his first business in 1937 – Tokai Seiki – making piston rings. When WW2 started Tokai Seiki was placed under the control of the Ministry of Munitions, like most companies that were useful to the war effort. His products were used in Nakajima planes and by the Imperial Japanese Navy.

However, Honda’s business was small compared to Kawasaki, Suzuki and Yamaha, so during the war he plied his trade as an industrial consultant.

He developed all kinds of factory machinery that allowed unskilled workers (the skilled workers had been conscripted into the military) to mass-produce high-quality products. His most famous wartime invention was a high-speed milling machine for Nippon Gakki (the musical instrument maker and parent company of Yamaha Motor), which allowed Nippon Gakki to dramatically increase its production of aircraft propellers for the Japanese air force.

Like Fuji’s Rabbit, Honda’s first venture into motorcycle production came through ingenuous use of wartime leftovers – a run of 500 bicycles powered by Mikuni generator engines, which had been used to power Imperial Army radio sets. When Honda started making its own engines in 1947, the company machined surplus WW2 shell warheads into crankshafts and conrods.

The next stage in the Big Four’s ascent was Japan’s first motorcycle races, established in the 1950s, including the Mount Fuji Ascent and Asama Highlands events.

This is where Honda, Suzuki and Yamaha established their credentials, competing against numerous other brands in races which were mostly off road, because Japan had very few metalled roads.

Honda’s first racing efforts were woefully inadequate because its four-stroke machines couldn’t keep up with its two-stroke rivals. But the company was learning fast – in 1954 Soichiro Honda travelled to Europe, where he visited motorcycle factories and bought a variety of machines to be studied and copied in Japan.

Domestic sales boomed. In 1959 Honda sold more than half a million Super Cub scooters alone, investing the profits in international racing to build the company’s global profile. That June, Honda became the first Japanese manufacturer to contest a grand prix event, the 125cc TT on the Isle of Man. The small team scored Honda’s first world championship point in the Ultra-Lightweight Isle of Man TT and won the team prize.

Two years later Honda won its first GPs and world titles. By 1967 it had won 140 GPs and taken more than thirty world titles.

Honda won its most famous successes in this era with its 20,000rpm 50cc twin, five-cylinder 125 and six-cylinder 250 and 350, mostly designed by genius engineer Soichiro Irimajiri.

Irimajiri’s quest for ever-higher revs to beat Honda’s two-stroke rivals led him to take advantage of a USA/Japan agreement, born out of Japan’s manufacturing role in the Korean war, which allowed Japanese companies to use American engineering expertise. Irimajiri travelled to the US, where aero manufacturer Pratt and Witney gave him the special steels needed to cope with the friction and heat created by his high-revving engines. Back home, he had the steel specs copied.

Si vous voulez, je pourrai ajouter la suite de l'article avec les paragraphes concernant Suzuki / Kawasaki / Yamaha.