1956 MZ ES250 Brochure

1956 MZ ES175

1965 MZ Motorcycle Program

1959 Simson 425S Brochure

1936 Auto-Union Program

1931 DKW R1000 Stationary Engine

In 1919, Jorge Rasmussen and Hugo Ruppe began showcasing an 18cc 'toy' stationary motor nicknamed "the boy's wish" at industrial shows. Often described as a toy motor, there was scarcely a market for such an expensive frivolity in post-Great War Germany. The true purpose of this first 'DKW' was as a demonstrator stationary motor targeting the small business market.

In the years before the Second World War, DKW would become the world's biggest motorcycle company as well as a major German automobile manufacturer, but a gigantic part of the company's business was stationary and industrial engines. These ranged from small, air-cooled single cylinder two-stroke engines to eight cylinder four-stroke engines, air-cooled and water-cooled, for use in cars, tractors, mowers, draisons, boats, water-pumps, fire-hoses, sprayers, electrical generators, in two-stroke, four-stroke and diesel format.


The stationary motor division of DKW was actually at the forefront of engine development, trialing every possible format. In 1931 they presented a four-cylinder inline water-cooled two-stroke motor, designated the RVW. The engine came in 1000cc and 1200cc capacity, with the 1200cc version generating 29 PS. Sales however proved to be very disappointing and only 100 engines were built, serial numbers 299001 to 299100. The engine was still being advertised in the 1933 brochure above.

Given the small production numbers, survivors are few. A complete example is held in a German museum collection (see postcard at the top of the post). A second example was discovered by Roland Servais in a Belgian scrap yard. Serial number 299035 was largely intact but some parts were missing.




Roland restored the motor and mounted it on a steel chassis and connected it to a French dynamo built by "Ateliers de Constructions Electriques de Lyon et Dauphiné" around 1925. You can see the engine in action in the video below:

Roland has decided it's time to pass the engine to a new custodian, so if you are interested in purchasing this extremely rare piece of DKW history, you can contact him here: rolandser@gmail.com
The engine is located in Belgium. Roland has other stationary motors too.

So why did DKW abandon development of the four-cylinder two-stoke? This is an interesting question, given that in a few years time DKW would come to recognize that the 600cc and 700cc twin-cylinder had reached its developmental limits and would begin scrambling to develop a new engine for their automotive range. They would, of course, settle on the 900cc triple, which in its initial configuration generated approximately 26 PS. In the RVW engine they had a motor that could generate at least 29 PS. It cannot be that this format engine wasn't suitable for an automobile engine because a remarkably similar engine was powering a range of Czechoslovak cars at roughly the same time - and this is where the story becomes intriguing.

Zbrojovka Brno was a Czech armaments manufacturer that branched out into automobiles in the mid-1920s. After developing their own series of two-stroke budget cars, in 1932 they sought to enter a licensing partnership with DKW. Two engineers were dispatched to Zwickau to work on the project, but DKW's licensing fees were too high for Zbrojovka and they walked away from the deals. The engineers however had learned enough from their time in Zwickau to design their own car from scratch in a period of only 9 months. This would be the Zbrojovka Z-4 ("Strong Four"), which went on sale in January 1933. The Z-4 was powered by a four-cylinder water-cooled two-stroke motor of 908cc, generating 16 PS. Later series were upgraded to 980cc capacity. The engine is strikingly similar to the DKW RVW, so it seems entirely possible to me that Zbrojovka's engineers had inspected the RVW engine in detail, or purchased one and reverse engineered it. Of course, this is only speculation but it's a plausible theory. Zbrojovka also used twin-cylinder two-stroke engines, derived from DKW technology.

Zbrojovka weren't the only Czech concern to seek a licensing agreement with DKW at this time. Jawa would enter into a licensed arrangement to manufacture the DKW F2 in 1934. DKW two-stroke motor technology would go on to power both their automobile and motorcycle range well into the 1990s.

Jawa car history: https://dkwautounionproject.blogspot.com/2021/02/jawa-700.html 
Zbrojovka Z-6 brochure: https://dkwautounionproject.blogspot.com/2019/10/1935-zbrojovka-z-6.html

1938 DKW SB350 Restoration Update - Coal Mining

After taking the bike for quick test ride it was apparent the engine was low on power, especially in first gear. There were a couple of items I decided I needed to check. The first was to clean out the exhausts, which I was certain were carrying some 80 years of baked in oil residue. The exhausts came out easily enough and quick tap confirmed my suspicions.

The lumps that simply fell out of the exhaust pipes were like little lumps of coal!

After a good tapping I had more than a handfull of coal.



A view of the baffles at the fishtail end. Pretty black.

Next step was soaking the exhaust parts in kerosene to loosen the oil residue.

A look down the silencer shows the state of the baffles. After soaking in kerosene I was able to scrub out a lot of the residue. It wasn't perfect but it was enough to clear the baffles.

Someone suggested to me that you could burn out the remaining residue, so I gave that a go. Unsurprisingly the exhaust 'fired up' and burned for about half an hour, relighting itself periodically with a big 'whoop!' After another round of cleaning up and scrubbing off dirt, mud, oil and rust, I reassembled the pipes and refitted them.

I took the bike on a test ride to the Arthur Grady Day on Saturday 17 May 2025. The exhausts smoked a bit and needed some tightening up afterwards. Power is still low, especially in first gear. Next thing to do will be to re-look at the gearbox and clutch lubricant as I think it may not be right. 
https://heinkelscooter.blogspot.com/2025/05/arthur-grady-day-may-2025.html

Previous step: https://dkwautounionproject.blogspot.com/2025/05/1938-dkw-sb350-restoration-may-update.html