Thursday, April 22, 2010

Das Kleine Wunder - the story of a remarkable engine

In 1906 a Danish engineer, J. S Rassmussen, founded a manufacturing company in the German city of Zchopau. The company initially built machinery for the textile industry, but in 1919 produced a small two stroke motor that could be fitted onto a bicycle. These tiny engines were remarkably efficient and could push a bicycle along at 40 kilometres per hour. The engines sold extremely well in post-WW1 Germany, leading Rassmussen to begin building his own bicycles.

An DKW bicycle fitted with a DKW detachable engine.

The success of the bicycle engine led DKW to experiment with new designs. In 1921 DKW released the scooter-like Golem, powered by DKWs 140cc stationary engine mounted between the riders feet. It wasn't exactly a successful design but led in its turn to the improved Lomos in 1922, which featured larger wheels and the engine mounted under the riders seat. The Lomos sold an credible 2,500 units and turned DKWs attention towards building real motorcycles.

The Lomos was a great improvement over the Golem, not just in name. Large wheels added to stability. The placement of the engine under the seat was also a vast improvement. Although very old fashioned, many Lomos' continued to be ridden well into the 1930s.

DKW's first real motorcycle was only a small step up from the motorised bicycles the company had been manufacturing to date. The stationary engine that had powered the Lomos was now mounted to the front frame of the bicycle with belt drive to the rear wheel. It wasn't a very efficient machine but it pointed the way to the future. Year on year the design was improved and sales steadily rose.

DKWs bicycle origins are clearly apparent in this 1922 machine. The 140cc engine was a real workhorse for DKW. It was originally designed and sold in large numbers as a stationary engine, it also went into the Golem and the Lomos and the first generation of DKW motorcycles, while both the Framo and Phanomen transporter companies independently installed the engine in their three wheeler delivery vehicles.

In 1927, DKW's engine design took a leap forward when chief engineer, Dr Ing Schnuerle, developed the inverted scavenging loop system that is still the basis of all modern two strokes. One key to the DKW engine's success was its impressive power to size ratio - able to generate up to 15hp and reach a top speed of 120kph for its diminutive 125cc displacement. In England and the US, motorcycle manufacturers were building heavy, multi-cylinder four strokes to get the same performance. The engine was also absolutely simple; there were only four moving parts and with only basic maintenance it could run forever. DKW's engine was so successful that by 1928 the company had become the biggest motorcycle manufacturer in the world, producing 65% of all motorcycles in built in Germany as well as supplying engines for many other German marques.

Nothing demonstrates the simplicity of DKW's two stroke engines more that their own 1939 DKW-Front brochure. The diagram on the left shows the Schnuerle process. On the right are comparisons of the moving parts inside the DKW engine and a standard four stroke.

DKW soon expanded its range to include a range of singles (from 100cc through to 1000cc), a split single that was used in racing engines, a series of twins and triples for use in cars. Nowadays, two stroke powered cars are looked at as an odd dead-end development, but that's just an accident of history. In the 1920s and 30s DKW built a wide range of quality cars powered by their little two strokes engines that were the equal of any of their competitors in styling and quality, but were cheaper, lighter and more economical. They also experimented with synthetic body panels. DKW soon became one of the biggest car manufacturers in Germany.

The DKW range of two stroke cars in the 1930s.

The tiny size of the DKW twine is clearly evident under the hood.

In 1931 DKW released the RT 125cc motorcycle. It was a lightweight, fast and stylish machine. DKW's advanced, production line construction techniques meant that DKW were able to pump out a record 60,000 units in 1932, the pinnacle year of their production. It was such a robust and reliable design that versions of this motorcycle would continue to run off production lines around the world for 30 years.

The RT 125 - DKW's "little wonder" would become one of the most influential motorcycles in history.

A 1927 film by DKW shows workers riding to work on their DKW motorcycles at the Zschopau.
Despite being the biggest motorcycle manufacturer in the world, the Great Depression took its toll, leading DKW to join with three other Saxon auto manufacturers, Horch, Wanderer and Audi to form Auto Union,the union symbolised by the four interlocking rings that we recognise today as the Audi logo. To avoid competition, each company was given a particular market segment to focus on. Horch retained the top end of the car market, building expensive luxury cars. Audi was virtually retired as a brand, building only a small volume of large saloon cars, and Wandereri built mid range cars. DKW however took the lions share of the 1930s market - low cost cars and motorcycles.

As with all other serious motorcycle companies, DKW took to motor-racing to demonstrate the power of its engines. In 1937 and 1938 bikes won the European championships, and in 1938 a 250cc racer achieved a world record speed of 183kph.

The 1939 DKW US 250 split-twin supercharged racer.

For more information on DKW's racing history:

Despite DKW's commercial success, the German army never showed any real interest in their motorcycle products, instead preferring the heavier 750cc BMW R21. Once the war started however, they adopted the NZ 350 as a dispatch rider's bike. The bike saw service in all theatres.

An Afrika Korps NZ350-1 at the Audi Museum. Between 1939 and 1943 DKW simply produced its civilian NZ350 for the army without making any changes to design or build, but in 1943 lack of aluminum led them to produce the NZ350-1 with cast iron pistons.

Post-war dismemberment...

Surprisingly, DKW's Zschopau factory wasn't damaged during the war but it by fate it was in the Soviet occupation zone. Some of the captured Auto-Union management  were executed by the Soviets for their use of slave and forced labour during the war, then the factories were stripped of everything of value and shipped it back to the Soviet Union. Surviving engineers and executives fled to the west, taking whatever intellectual property they possessed with them.

All the Allies were keen to get their hands on DKW's designs. The British and Americas claimed them as war reparations, but the Soviets were less concerned with legalities and simply dismantled the Zschopau plant and shipped it to Izkevsk in Russia and between 1946 and 1951 the Russians built 127,000 NZ350's under the IZH trademark.

The Minsk Moskva - the start of a long and venerable line of Soviet 125ccs.

The IZH 350 wasn't the only DKW knock-off the Soviets produced. They also began manufacturing a version of the RT 125 as the M-1A Moskva in a factory outside Moscow. In 1951 the plant was relocated to Minsk in Belarus. From then on Minsk specialised in 125cc motorcycles, exporting hundreds of thousands all across the socialist world. The collapse of communism and direct competition with cheap Japanese exports placed the company under extreme financial pressure however, and in 2005 the Belorussian government intervened to prevent the company going into receivership. Although its survival remains tenuous, Minsk continues to produce 125cc motorcycles today.
Richard Hammond rode one during the Top Gear Vietnam special.

And meanwhile in England
In Britain, the designs for the RT 125 were handed over to BSA, but initially no one knew what to do with them. Such a small engine just seemed to have no market in Britain where four strokes dominated the market. In 1948, BSA took a leap and developed the RT 125 into the Bantam in response to a potential export contract. The contract fell through however and so the Bantam was released in Britain, where its low cost and reliability made it an instant winner. The Bantam would become one of the best selling British motorcycles of all time, with a production run from 1948 to 1973 turning out almost half a million units.

For many in post-war Britain, the 'little rooster' was their first ride.

BSA's subsidiary, Ariel, also received the plans to DKW's parallel twin 250cc engine which they eventually used in their radical new motorcycle design, the Ariel Leader in 1958.

Although the Leader's styling was unique, the engine design was not. It was based on DKW's proven parallel twin, a design also copied by the German company, Adler.

Across the Pond
In the US, Harley-Davidson had also received the designs for the RT 125 and in 1948 released their version as the Model 125. For Harley-Davidson, who specialised in big twin four strokes, this was their first foray into two stroke engines. In 1953, the engine size was increased to 165cc, but in 1955, they reverted back to the 125cc engine and renamed the bike the Hummer. It would continue in production until 1959.

Not quite the whole hog... and a two stroke to boot!

In 1960 Harley-Davidson used a 165cc DKW two stroke in their scooter, the Harley-Davidson Topper. The engine was built by the Italian motorcycle manufacturer, Aeromacchi, whom H-D had partnered with to build the Topper. Ultimately it wasn't a successful venture.

Long regarded as a failure (it was), the Topper is now quite sought after due to its rarity.

And in the far east
Even in far away Japan the RT 125 was making its mark. In 1955 Yamaha reverse engineered an RT125 and releasing it as the YA-1. Exactly where they acquired their pattern is uncertain. It could have been from a German import, a Soviet version picked up in China, or even a copy of a Harley-Davidson Hummer acquired from US occupation forces. Regardless, the YA-1's design origins were clear. In later years Yamaha would copy the NZ35o and other German machines, like the Adler 250cc. Parallel twin two strokes following the DKW/Adler design would be copied by other Japanese manufacturers including Honda, Suzuki and Kawasaki and be produced in their millions right up to the present day.

Dejavu.... again.

And Resurrection.
After the loss of its Zwickau factory DKW re-established itself in Ingolstadt in West Germany and began manufacturing the RT 125 and NZ 330 motorcycles. Car production didn't restart until 1948. In 1955 DKW attempted to break into the scooter market with the Hobby. Powered by a small 75cc engine, the enigmatic little scooter featured automatic, variable speed drive that gave it a surprisingly nimble performance. But the Hobby didn't sell as well as DKW hoped so they sold the manufacturing rights to the French scooter company Manuhurin which continued producing it into the early 60s.

I almost bought this gorgeous 1955 Hobby when I bought the Troll in 2008. It was very tempting but I decided that buying three scooters would just be a little too extravagant.

In 1958 DKW re-entered the moped market with the beautifully styled 49cc Hummel, but once again it failed to be the success they hoped for. In 1960 DKW's moped arm merged with Victoria and Express to form Zweirad Union. ZU continued with the Hummel and various derivatives for a number of years.

The DKW Hummel was space age in its styling but never a big seller.

Daimler-Benz bought out DKW and the Auto-Union in 1957 but its continued financial decline led them to sell it to Volkswagen in 1964. Volkswagen was not so keen on maintaining DKWs line of economical two stroke cars and wound up DKW in 1966, reviving the Audi brand instead.

A life at half speed - East Germany
But of course that wasn't the end. In East Germany, the Zschopau factory was resurrected by VEB, the state owned auto conglomerate in 1948. In 1950 they began producing versions of the RT 125 and NZ 350 under the name IFA (Industrieverband Fahrzeugau AG).

An IFA and a MZ version of the RT 125cc at the East German Motorcycle Museum in Berlin.

IFA even resurrected DKW's racing heritage to compete in European championships.

In 1956, IFA was renamed Motorrad Zschopau, or MZ for short, and were soon producing a range of engines for their motorcycles varying in size between 125, 150, 175 and 250. MZ supplied the engines for the IWL range of scooters and Simson mopeds. In fact, VEB cancelled all four stroke engine development for cars and motorcycles in favour of the cheaper and simpler MZ engine.

IWL's Pitty and Wiesel featured the DKW 125cc engine. Whilst it could push the little RT 125 along at a cracking pace, the engine really struggled to move these heavy beasts. In 1959 MZ increased the engine size to 143cc for the IWL Berlin and Troll. They were still underpowered though.

In 1962 the DKW 125cc engine, now more than 30 years old appeared in a new generation of MZ motorcycle - the ES125. The ES range led on to the distinctive styling of the MZ Trophy, East Germany's successful export motorcycle.

A group of early MZ ES and ETS models at the East German Motorcycle Museum.

MZ stuck with its two strokes until 1990 when it introduced the MZ 500-R four stroke. Unlike other Eastern European motor companies, MZ had built a strong export market for their motorcycles which enabled them to survive the transition from socialism to capitalism a little better than most. However, by 1993 MuZ (as it was then known) had pretty much lots its domestic market to Japanese imports and went into receivership. Its motorcycle production facilities were sold to the Turkish Kanuni motorcycle company, which still produces new bikes and spares for almost the entire range of MZ machines - which makes restoring an IWL or MZ bike far less taxing than it could be!

In 2010 the MZ company was revived by two former MZ racing identities. The company is once again manufacturing motorbikes and scooters, albeit on a small scale.

Here is a German video documentary about DKW and MZ.

IFA did not disappear with the name change in 1956. IFA took over the Audi production facilities at Zwickau to manufacture a range of heavy duty trucks and the East German 'people's car', the Trabant.  , The Trabant was powered by an air-cooled, two cylinder two-stroke engine based on a prewar DKW motorcycle engine. 3 million Trabants would be built before production ceased in the mid 1990s.

The infamous two stroke Trabant engine was the direct descendent of DKW's two stroke motorcycle engine developed in the 1930s.

When it comes to longevity, there is little to compare with DKW's two-stroke engines. Their 125cc really was the first modern, reliable two stroke and its modern derivatives are still manufactured by Honda, Suzuki, Kawasaki and Minsk today - almost 80 years after they were first invented.


  1. Unfortunately the section relating to the DDR operations is confused and inaccurate (eg. MZ did not make engines for Simson, who were a completely seperate operation in a different area (Suhl, Thuringia)& there was no "organisation" called VEB (Volkseigener Betrieb - or "State owned enterprise), hence VEB Motorradwerk Zschopau, VEB Pentacon Dresden (cameras) VEB Filmfabrik Wolfen (camera film) VEB Automobile Werk Eisenach (Wartburg cars).
    IFA was the organisation that oversaw all vehicle production in the DDR, from bicycles to tractors.
    Kanuni has not produced MZ motorcycles for years & unfortunately neither has MuZ, which was closed by their bank some years ago & is the subject of ongoing legal processes as a result.

    1. You are right. The section on East Germany was written a long time ago when I could find little information in English. I've since realised some of it is quite wrong and I need to revise this. Thanks!

  2. Interesting read trying to find out who developed the berini