by dub » Sat Oct 08, 2011 6:02 pm
What do you weigh? About 85kg??
I've no idea what the stock spring is but your z750 weighs the same as my z1000 and that has (OEM) a 10.5 kg spring in the back with only preload adjustability.
If you want a softer shock, the 08/09 zx10r shock spring was 9.1kg. If you want to go softer again, have a look at the 06/07 zx10 shock, they had a 8.3kg spring (although, even with your skinny arse I reckon that would be too soft). I went the 04/05 zx10r shock on my z1000 as that was a 10kg spring and was a much better quality piece of kit. I think the more recent 6's had 9.7kg (my memory gets hazy about the 6's as I really only looked at the 10's).
BTW, I think it's worth a call to the old owner to find out the work that had/had not been done to the existing suspension. It would be good to know what your are starting with.
2004 Z1000
1982 GPz750