I was looking through the list of Kop Hill Climb entrants and came across this one:
"1978 Silk 500RS 500cc
George Silk - DERBY
Engine has been rebuilt from original castings, gearbox is original with 6 speeds instead of the original four.Frame adapted to cater for water cooled engine."
Looks like George Silk has put together another 500cc bike. The six speed gearbox sounds interesting. Next time I see the other 500cc bike I'll ask how many gears that one has. Hope to get a look at the George Silk bike at the Hill Climb event in September.
Lots of interesting older bikes in the paddock display and entered for a run up the hill.
Sorry as far as I am aware all 500s (the two up till now) that I have seen are your std 4 speed. While George has a workshop he will keep designing things. There is no stopping him! Watch his space.