As stated in one of the earlier posts fix the rear first, anything over 20stone will need a spring change on the S1000rr shock.
Dropping the front will only make it turn in faster, the Fzs1000 has a tendency to run wide out of bends especially when giving it the beans and dropping the front won't fix that, it needs a lot of work to reduce/stop it.
It can be done with just upgrading the fork springs and increase the the fork oil to 7.5w minimum, playing around with the compression and rebound damping, but is a slow process
I have noticed over the years that oils from different companies do not work the same even if they have the same weight markings.
Running wide out of bends is exactly it ! I’ve wound the preload in to no rings showing and it still dives badly. Using 110mm of travel on spirited riding with some hard braking. It seems the first 2 inches of the spring are just pure sag and slop , maybe someone put progressive springs in at some point. Either way they’re pretty shagged, time for a rebuild
On EU models standard fork springs are progressive and go from .83kg to 1.2kg but the US imports are softer at the top .78kg. I changed mine to stiffer wilbers progressive, but still found the soft setting to soft but not as bad as the originals. I did not go linear because I go two up a lot.
With the original springs and original oil (which is about 5W), I used these settings to start (I'm about 13.5 stone with all gear on)
Front: drop forks 5mm through yokes.
Compression: five turns back from max.
Rebound: six turns back from max. finally took it in to 4, improved the running wide a bit.
Preload: maximum no rings showing.
With Wilbers and 7.5W oil
Front: drop forks 10mm through yokes. (12 to 15mm made it turn in top quick with the Sportec M7RR)
Compression: six clicks back from max. Started at eight and worked back
Rebound: four clicks back from max. Started at 8 and worked back
Preload: maximum no rings showing.
I found that the rebound had more effect as I felt it appeared to be rebounding too quick and causing it to run wide, by slowing the rebound it improved.
The problem was I used different make of oil last time and my original settings before that no longer worked.
A word of caution when putting the forks back together if you strip them, set the rebound adjusters off the bike to half way, it is around 40 clicks from soft out to hard. Otherwise you may end up not being able to adjust it properly when assembled. Otherwise you may not be able to adjust them to full hard, I found out the hard way