If memory serves, these bikes all have a clevis as lower shock mounting point and a significantly lower linkage ratio than the VFR with correspondingly (much) lower spring rates. These will require some serious mods to be usable.
Older CBR 600 F and CBR 900/929/954 were more similar to the VFR but the V4 architecture and the LBS/ABS plumbing also puts physical space at a premium so even these do not fit all that well.
DMr offer the CBR F4 shock for the 6G and the 929 for the 5G. They are the best fit but they still require mods to get the proper length and access to the adjusters may not be all that great, especially preload on the 6G/F4 swap.
This is what i suspected about the newer bikes.
I will be pulling all the linked braking and associated brackets. Is the 929 shock preferred if it can be made to fit?
I have herd there is a special wrench that makes the f4i preload more feasible.
Not sure what you mean by 'some results' from RT. At your weight, RT recommend a 17.8 kg/mm spring for the 6G.
To 'calculate' spring rate you need to have some pretty accurate figures for sprung weight, weight distribution and, most importantly, linkage ratio. These are not very easy to come by and the linkage ratio is a VFR peculiarity (significantly higher leverage than most anything else on the market these days).
If you used another bike on the RT calculator and input the VFR's weight, that might give you acceptable results for the forks but the shock will likely be way off.
That seems unlikely. Check your sag, adjust your preload accordingly and play with the damping adjuster a bit.
The (admittedly pretty rubbish) stock shock is softly sprung but can be adjusted very hard, especially at your weight. I'm over 210 w/o gear and it kicks like a mule if I give it too much preload and turn the adjuster near full hard.
Ahh i must have been using the wrong calculator when I was crunching some numbers. Makes me wish I could go try more suspension settings, (damm snow!) as I haven't gotten this bike to turn at low speed as I would like.
So 0.90 springs for the front and 17.8 for the rear. Would the stock 0.85 vfr springs work in the F4i forks?
Any suggestions on re-valving either the forks or the rear shock?
Thanks for replying RC36!