Boxing Clever: 1938 Zündapp K800

The K800 flat four was the apogee of Zündapp’s model lineup, and is undoubtedly one of the world’s great motorcycles.

  • 1938 Zündapp K800.
    Photo by Kyoichi Nakamura

1938 Zündapp K800
797cc air-cooled sidevalve horizontally opposed 4-cylinder, 62mm x 66.6mm bore and stroke, 5.8:1 compression ratio, 22hp @ 4,300rpm (at rear wheel)
Top speed:
75mph (60mph w/sidecar)
Single 22mm Amal (German)
4-speed, hand-shift, shaft final drive
6v, Bosch distributor w/coil and breaker points ignition
Pressed steel duplex cradle/55.1in (1,400mm)
Pressed steel girder fork front, rigid rear
7.5in (190mm) SLS drum front and rear
3.25 x 19in front, 3.5 x 19in rear
Weight (dry):
473lb (215kg)
Fuel capacity/MPG:
4gal (15ltr)/NA
Price then/now:

Before its sudden fall from favor in the 1970s, Zündapp was arguably Germany’s most successful motorcycle marque, and was certainly one of the pioneering brands in the European motorcycle industry. The K800 flat-four produced in the years before World War II was the apogee of its model lineup, and is undoubtedly one of the world’s great motorcycles.

Zündapp has become the forgotten brand in Germany’s two-wheeled history book. Yet after commencing bike production in 1922, it was for many years the country’s largest motorcycle manufacturer — albeit post-WWII in the western half only — and as recently as 1977 produced as many as 115,000 bikes in a single year, before sales of its by then predominantly 2-stroke range suddenly slumped in the face of Japanese competition, sending it just seven years later into the hands of the liquidator. But for over six decades Zündapp was at the forefront of the German motorcycle industry, and it surely ranks alongside BSA, Norton, Indian, Moto Guzzi, Triumph, Gilera and Harley-Davidson, as well as its BMW rival, as one of the most significant pioneer marques in two-wheeled history.

In the 1930s, Zündapp produced a pair of 4-cylinder K-series models — the “K” name tag denoting that they employed shaft final drive, or Kardanantrieb — with completely individual architecture, unlike their smaller-capacity brethren, which shared the same basic flat-twin layout as BMW’s boxer models.

1933 saw the debut of Zündapp’s first-ever horizontally opposed flat fours, the K600 and its range-topping K800 sister, both designed by Richard Küchen to feature his innovative design of 4-speed unit construction transmission, whereby sprockets and chains replaced the shafts and gear pinions of a more conventional gearbox. In solo form these positioned Zündapp at the top end of the market — its BMW rival never produced anything with more than two cylinders — while in sidecar guise they also allowed the company to offer models with much more power and especially more torque than were available elsewhere.

Order the November/December 2016 issue of Motorcycle Classics to read more about the 1938 Zündapp K800. Contact Customer Service at (800) 880-7567 or contact us by email

David O’Rorke
3/9/2018 5:42:03 AM

An interesting article on Zundapp products. A pity it did not go further by mentioning the development of the KS750, which was a sidecar machine with forward & reverse gears driving the rear wheel and the sidecar wheel also. The design was perfect for wartime use and well suited to Saharan sand & Eastern Front mud in particular. Hitler advised BMW’s engineering boss to go over to Nurnburg to assess the possibility of duplicating production in BMW’s Munich plant. When he reported back that it was too complicated for BMW to produce, Hitler ordered him to do so. The result was the R75 which many people assume was the only such machine. It was good but not as strong as the Zundapp KS750. Another myth is that the Eastern Front was littered with broken-down Zundapps with (unbelievably) snapped gearbox chain problems! That is mindless prattle as the fully gear driven drive train of the KS wartime product was an innovation which was immensely strong and capable. As ever the motorcycle world abounds with bull-shit and half-truths. The best thing is to read up the facts and then smile quietly at the torrent of crap poured out by all & sundry (such as Lawrence of Arabia died on a Vincent Black Shadow!!!! How do they dream it up?) Dave O’R

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