Standard springs are dual rate with a soft part and a harder part. Overall they give about 0.65kg/mm Switching to single rate springs you would be looking at 0.85kg/mm or 0.9kg/mm
they were 9.5 as they had to support a heavier rider. Just been rumaging in the garage as I am sure I had a set of springs somewhere but cant find them. I thought I had the old set of springs from Matt T's old SS 600. Think they were 748 / 916 springs. If I have them will bring to Oulton. Mark