It's a Kriedler, (Dutch). Brian Woolley was a noted (British) tuner of small 2-strokes, and built some fearsome racers. He died 5 (?) or so years ago.His collection of bikes was taken over by Richard Rosenthal of The Classic Motorcycle magazine here in the UK. Perhaps you could contact him as he writes a "You were asking" column in the mag.
REgards, Mark