The Austrian built SIWA machine, the engine and frame being made by Siegfried Wartblichter whilst his brother, Kurt was the rider on these machines.
The brothers made in total about 5 different engines, mostly by using Jawa parts. The very first SIWA engine was a JAWA bottom half and on top, a SOHC 2V PORSCHE 935 head.
The engine on the photo* is again very much inspired by the JAWA DOHC 2V iceracer, but as you can see all parts are different and home made. A very interesting detail is the extra outside flywheel mounted on the primarily drive side.
Ridden by Gunther Bauer of Germany, this machine has a Jawa engine. The 1999 model is recognisable with its fueltank placed in the normal position whereas the the model for 2000 has the fuel tank mounted in a forward position.