Hello Greybeard,
besides my GF Plunger I own a Zündapp K500 (sv boxer, 500cc) and the K800 is in fact almost the same bike - except the bigger engine. The Zündapp K800 is a 4 cylinder side valve boxer engine. The picture attached shows some internals of this interesting engine. In its time, it was an outstanding design - but it has some problems. The designer Richard Küchen and his brother Xaver had set the priorities according to "function follows form" ... the engine is a monolith and the machine sounds great - but it was not "Autobahn-proof".
The K800s are rare but an eycatcher if seen in an event. In a few weeks I plan to be part of such an event with my K500 and I am sure to see at least 3 to 4 of the K800s
Best regards. Manfred
