The origin of the motor

Hi, if anyone has suffered from such an engine? I only know that it is the engine with a capacity of 250 cm3. The absence of any numbers or characters. Apparently, this may be the BMW engine but no one is sure ... please help

http://s3.ifotos.pl/img/foto1_hewwnha.JPG
http://ifotos.pl/zobacz/foto3_hewwnrn.JPG/
http://ifotos.pl/zobacz/foto2_hewwnre.JPG/

I have seen one..

Many years ago at the West of England steam show, I cant remember what it is and it was a time before I could afford a Camera.

This is a similar engine, if not the same.

http://www.stationary-engine.net/Nuenen2009/Nuenen2009126.htm

I cant quite remember what the gentleman told me about them, would have remembered if he said BMW, Think it was something being with D, but as it was 6 years + ago my mind is drawing a blank.

Was very nice and ran lovely, tried to liberate it lol

Cheers Steve