The Factory version of the Yamaha HL500 as designed by the famous Swedish former World Champion Sten Lundin was a remarkable bike.
This Yamaha HL500 "Factory" machine was the last 4-stroke to win a Grand Prix Motocross before a very long period of 2-stroke domination began. Bengt Aberg won the Luxembourg Grand Prix on this very machine.
Several people now try to copy this bike, to my taste they all look too "polished" and they lack the "real guts". (This one was built by "real" Champions). Today (290308) I finally found the color pictures of the original bikes and you can enlarge them !
Fried Anepool, an old Dutch friend and the founder of the very large Dutch XS650 Club (April 1988 and more than 600 members): www.xs650.nl found my site and told me that he had been to this very race in Luxembourg. (That will be a real "special" story on its own). He made some terrific pictures of Bengt Aberg on the big "thumper" Yamaha.