You can call it whatever you want, but it was a winner. A 1936 250cc supercharged Auto Union DKW: http://www.mcnews.com.au/ClassicsCustoms/Museums/BirdWood_dkwrs2_full.jpg http://www.mcnews.com.au/ClassicsCustoms/Museums/BirdWood_dkwrs_full.jpg Doesn't that gas tank's style look like a 1979 Honda CB-750F? Come on. You know it does. A 3 cylinder water-cooled two stroke, blessed with 2 heads and 4 con-rods. This is the legendary DKW brought to Australia for the 1937 S.A. TT on the winding 8.75 mile street circuit at Lobethal S.A. The bike found its way down under during a "cultural and sporting exchange" with that most cultural and sporting nation, the Third Reich! DKW's No. 1 works rider, Ewald Kluge, brought a rotary valve 250 with him as well as this rigid-framed supercharged model as a spare practice bike. The Deek features a third forward facing cylinder which acts as a "kompressor" to force the fuel mixture into the two vertical cylinders. The smaller front cylinder operates the transfer ports and the rear cylinder fires the mixture. Although never revved over 3700 rpm the DKW's twin port exhausts and megaphones delivered an alarming noise, best remembered as being reputedly loud enough to hear on the English mainland when being raced on the Isle of Man. The frame is all welded and accommodates a radiator between the front down tubes for the essential water cooling system. Wanna *buy* one? http://www.motoclassic.ch/sites/gallery/Konol-rechts.html http://www.motoclassic.ch/sites/frame_en.htm (click on "Restoration Details for picture of crankshaft and arrangement of the three pistons) The Split Single two stroke is an antiquated idea that was brilliant in its day. And, whilst searching for the relationship between DKW and Puch, I found a patent abstract that shows some inventor seems to have picked up on the idea for use on 2-stroke powered tools that can't make use of an expansion chamber. Puch (Austria) started using the concept for motorcycles in the twenties. Their first split single being designed by Giovanni Marcellino. The configuration was adopted by Ing Zoller in 1931 and was to make DKW (Germany) the dominant racing motorcycle in the Lightweight and Junior classes during the pre war years. Up until then TT races were won by overhead cam fourstroke engines, the conventional two stroke engine of the day just was not good enough. DKW also employed a third piston (3 cylinder single) which acted as a supercharger to force feed the crankcase. DKW tried piston port, reed valve and disc valve induction and had their greatest success with the disc valve setup. The classic Puch layout (for street engines) was three transfer ports in the back cylinder with two exhaust ports and either one or two inlet ports also in the front cylinder (piston controlled inlet). The forked conrod had a main roller big end with a secondary sleeve bearing pivot pin at the fork in the rods. Zoller's design used two rods, and a lever arm that rotated with the crankshaft. This allowed one piston to move faster than the other. http://img139.imageshack.us/img139/6195/dobbelstempel7vv.jpg A major draw back of the split single design was the mass of two pistons and conrod(s) when compared to a conventional single. The main reason for the split single idea was to have the exhaust port open before the transfer ports then close before the transfer ports thus preventing loss of fresh charge out the exhaust. The idea worked well with an extractor exhaust system and or a supercharger but when Walter Kaaden introduced the resonating exhaust system (expansion chamber) that relied on the transfer port shutting prior to the reflected wave of gas being rammed into the cylinder the day of the split single had ended.
It does, actually yes. Or maybe a Yamaha XJ900F. Sammy Miller has one of these in his museum on the English south coast. http://www.sammymiller.co.uk/ There's a *great* Quicktime panorama on that site. What makes his museum so *good* is its eclecticism. He's got everything there - road bikes, dirt bikes, race bikes, from all over the world. Whatever he thought interesting. So there'll be an AJS Porcupine, and a lovely little Benill 250cc four road bike from the early 1980s. A set of Yamaha YPVS barrels to play with (because he rightly considers them innovtive and important), and an old set of girder forks.
