Stock Rear Spring Rate? R6 shock installed

[SquadraCorse]

I installed a 2007 R6 rear shock this past weekend and it feels like the rear spring is way too soft. I'm getting 40mm of rider sag, but I feel I could bottom the shock out easily. From what I have come across online the spring rate is about 560lb/in for the R6 spring. I know that's lower than the FZR600. Does anyone have an accurate number for the stock rear spring rate in the FZR600? What rates are you guys running on your FZR/R6 shock setup?

[rotortech]

SquadraCorsa,

I don't know what the rates are but the FZR spring is stiffer than the R6 spring. I even did some hand calcs but I can't find the data right now. I had read that the FZR spring was not enough if you weigh over 160 lb. I weigh about 195 with gear so I swapped the FZR spring on to the R6 shock. I works great. Sorry, I didn't measure sag yet.

Here are some unverified numbers that I found and believe to be representative of the spring rates:

R6 485lb/inch
FZR600 728lb/inch

[SquadraCorse]

Thanks man, you didn't have any problem running the fizzer spring on the R6 shock? It's noted as a 6" spring whereas the R6 is 5"? I would like to start from the factory spring rate as a baseline, but didn't know if I'd be better off getting a 5" spring with the FZR rate or just running the stock spring.

[rotortech]

Free standing height of both my springs were the same. Sorry, I don't know what I did with the measurements.

Here is what I had to work with:



The R6 spring is the red one that was removed and the FZR spring is the black one that is installed. I highly recommend a spring puller for this job to avoid injury and death. No joke. Here is a nifty puller that I bought on eBay for about $30.



Here is it is in action:



You might be able to rig something to get that R6 spring off but the FZR spring is a monster to compress safely. If it gets away from you when compressed it will go through your body.

[mrfreeze5]

Ive got a stock R6 shock and spring and it feels perfect for my bike. But then again, my bike is lighter than your average FZR, but it seems to be a perfect compliment to my YZF swingarm. I had to make minimal adjustments to the dampening before I was really happy with the ride. Im 170lbs + gear.

In other words: do a swingarm swap

I havent seen anyone put a FZR spring on a R6 shock before due to the different lengths, but its pretty common on the FZ1 shock swap since the springs are the same length.

[Yamster]

I have put a newly coated FZR spring on my R6 shock.
Seems to fit perfect,and with the spring rate of the standard spring being spot on for my weight,job done.
Will post some pics.

[rotortech]

Ive got a stock R6 shock and spring and it feels perfect for my bike. But then again, my bike is lighter than your average FZR, but it seems to be a perfect compliment to my YZF swingarm. I had to make minimal adjustments to the dampening before I was really happy with the ride. Im 170lbs + gear.

In other words: do a swingarm swap

I havent seen anyone put a FZR spring on a R6 shock before due to the different lengths, but its pretty common on the FZ1 shock swap since the springs are the same length.

As you can see from the photos that I posted above the spring lengths are very close and they are actually the same in the free state. There must be other years of R6 shocks with different length springs?? A swingarm swap to avoid changing a spring seems a little heavy handed to me. Mr. Freeze, you have the R6 shock with the YZF swingarm. What pivot are you using? The typical R6 shock swap on the FZR600 uses the FZR pivot which has reduced mechanical advantage compared to the R6. That is the reason for the difference in spring rates. I am wondering if you have used the YZF pivot that works better with the R6 spring. Just wondering.

[SquadraCorse]

Regardless of bike weight the massive difference in geometry between the R6 and FZR swing arm and associated linkages leads me to believe that going 200lbs lighter on an fzr rear spring (i.e. using the R6 spring) would be far too soft.

I pulled the FZR spring off the old shock yesterday using an automotive spring compressor I machined to fit the motorcycle coils. I'll powder coat it orange this weekend and put it in and then tune from there.