Ok, I've got some rear spring rates here. Got a kat600 shock and installed it today. I was hoping to measure the spring rate with a scale, but that didn't work out so well... However, using this calculator- http://faq.f650.com/FAQs/ShocksSpringRateFAQ.htm  I took some careful measurements and came out with some believable numbers:

Stock rear spring ('02 model FWIW)
0.394 inches (10mm) wire diameter
2.44 inch (62mm) coil diameter
5 free coils
=8.7 kg/mm (487 lbs/in)

kat600 rear spring ('06 model FWIW)
0.472 inches (12mm) wire diameter
2.73 inch (69mm) coil diamter
6 free coils
=10.7 kg/mm (597 lbs/in)

Per pic above, the kat750 spring is listed as 10.9kg/mm
Using my method and the calculator, assuming it's the same diameter as the kat600 spring, I'm getting 10.7. 10.9, 10.7, whatever, seems pretty close to me and gives the method some validity. So it appears the kat600 and kat750 springs are very similar if not the same rate. The damper may very well be different.

So, the kat600 spring (and maybe the 750 too) is ~23% stiffer than stock. 

With the stock rear, I had it set to position 6. Before removing the shock, I found this to give me 28mm of rear sag. That's for me with some clothes on (195lbs) and a full tank of gas. With the new shock, i tried it on position 1 first, 40mm sag. Position 3 got me to 33mm. Close enough. I'll likely have to adjust it once I do the front springs anyway. Speaking of which, the front sag was 62mm!! 

Per this- http://www.triumphnet.com/st/acc/racetech/setup.htm and other info on measuring sag, I'm shooting for ~30mm on both ends.

Guys, I'm considering picking up this Katana shock. It's described as being in very good condition but it's off a 1995 Suzuki Katana 600 GSX600F.
Finding it hard to find a decent one. Even shocks looking worse than this are going for $70-120.
Although it's old it actually looks fairly clean like it hasn't been used much. 
One thing I noticed is a black spring shaped mark beneath the springs on the rod in the first picture.
Does anyone know what that indicates?

Quote from: Toner on June 05, 2018, 05:06:43 AM
Guys, I'm considering picking up this Katana shock. It's described as being in very good condition but it's off a 1995 Suzuki Katana 600 GSX600F.
Finding it hard to find a decent one. Even shocks looking worse than this are going for $70-120.
Although it's old it actually looks fairly clean like it hasn't been used much. 
One thing I noticed is a black spring shaped mark beneath the springs on the rod in the first picture.
Does anyone know what that indicates?

Figured it out while cleaning my old shock. It's the reflection of the spring 

Fit it in the linkage and make sure it doesn't hit the linkage thereby bending the shock. There is a spot you can grind that linkage a bit. BTW this looks like a deep clevise shock. May not need the linkage grinding, just make sure.
Cool.
Buddha.

Hey shock masters, installing my 2006 kat750 shock to my 04 gs500 to replace my blown out old one and compliment my .90/15w front end. Shock spring touches front of swingarm by about one metric hair and the bottom shock bolt won't line up by about 1mm give or take. Wherabouts can I fenagle for clearance or grind stuff?

Also interesting note, my crummy gs shock allowed the rear tire to touch the ground on center stand, the kat750 shock holds the tire about an inch off ground (seems right).

Any help greatly appreciated!

I had to grind a cun't hair off my swingarm right in the middle of the "U". Then I could fit my shinny red shock in there. Really, that's what I did. Then, then I could fit my bolt in the hole and screw my nut on.

Thanks pliskin, really appreciate it. I will grind a little off.