My '78 CB550 has now covered the mighty mileage of 16500 miles and all seems well.
The rear suspension consisist of a pair of genuine Koni shocks with 3 position pre-load. Unfortunately these are too long and there's a big gap between the mudguard and the wheel and the wheel touches the road when it's on the main stand.
I've done some measuring and investigation and it appears that the shocks are for the SOHC 750 and 650.
The distance between the mounts is 339mm (should be 319mm) and the bottom mount is forked.
Before I do anything I thought I'd ask here first so does anyone have a good pair of 550 (or 400/4) shocks which they'd like to swap for my Koni's?
If not I'll buy a replacement pair and sell the Koni's, or put them on Ebay.