Here's a quick chart of stock spring rates on the little Ninjas and GSXR shocks, taken from
RaceTech's calculators. This is just to make it easier to see which bikes have which spring rates. I don't know if all of these shocks can be easily DIYed or if the springs will swap between all the different GSXR shocks.
I've also included the ideal rider weights for race and street from
RT's NewGen calculator. These are just numbers based on RT's formula, not race-proven experience. They're not gospel, but they should give you an idea what spring rate you should be looking for and/or how far off your current spring is. Note that in
his suspension thread a while back, rojoracing53 said that RT's calculator gave results that didn't match his real-world testing, and that the stock rear spring still seemed to be too soft for his
(unspecified) 160lb weight.
Code:
BIKE MODEL RATE (kg/mm) RATE (lb/in) RIDER (lb)
EX500 OEM 5.4 300 <30
PreGen OEM 7.9 440 136-144
NewGen OEM 9.3 520 209-218
98-00 GSXR600 6.4 360 58-64
01-03 GSXR600 8.0 450 141-149
04-05 GSXR600 7.6 425 120-128
06-09 GSXR600 9.4 525 214-224
11-13 GSXR600 10.1 565 250-261
00-03 GSXR750 7.2 400 99-107
04-05 GSXR750 7.3 410 105-112
06-07 GSXR750 9.5 530 219-229
08-10 GSXR750 9.5 530 219-229
11-13 GSXR750 10.5 590 271-282
01-02 GSXR1000 7.7 430 125-133
03-04 GSXR1000 8.6 480 172-181
05-06 GSXR1000 8.1 455 146-155
07-08 GSXR1000 10.1 565 250-261
09-11 GSXR1000 11.6 650 329-341