Static Sag???

[Science]

Jeremy, ( or any of you backyard tuners)

What's up w/static sag? I have an'02 YZ-250, weigh 225lbs, & race Vet B. I'm working w/a local Race Tech shop & they reccomended, .47 fork springs & 5.2 shock. This seems to balance the bike well, but w/95mm of rear sag, I don't have any static sag. Should I move the rear up to a 5.4? Or will it be too harsh?
I'm fairly happy w/it as is.
Any info would be helpful!
Thanks!

 

[dbrace]

Guess what? your race tech guy wrong. You need a 5.6kg spring. For your bike static sag needs to be between 15 to 30mm. There is no way you will get that with your spring. Most of these guys dont have a clue and can only give you what the chart says. Setting your shock sag and then choosing the correct fork springs to keep the bike balanced is, i beleive the first step in setting up your suspension. If he cant help you get that right why bother?
If you run springs that are too soft the suspension will ride way to low in the stroke and cause a number of handling problems. Good luck.

 

[jaguar]

Putting in his data in the MX-Tech web site I got these recommendations:
Your stock fork spring rate is.....44kg/mm
Your stock shock spring rate is....4.9 kg/mmkg/mm
Your recommended shock spring rate is....5.12kg/mm
Your recommended fork spring rate is....0.4625kg/mm

But I don't see why there'd be no free sag if the race sag is correct. Are you sure how to measure it? Tell me how you did it.

 

[HONDA65]

I can tell you from personal experience that a 5.2 is to soft. For '01 and '02, RT's rate recommendations were a little soft for the YZ's. But I had to learn this through trial and error. I might hesitate in going to a 5.6, though I bet it would fall within sag specs. If your local RT guy is willing, I'd try a 5.4 first, and if sag/free sag measurements are in the ball park, run it and see how it feels. sometimes i can get 2 different springs to fall within the appropriate ranges (obviously one will be towrd the softer end and vise versa) and then its all a matter of personal taste. Though I'm fairly aggressive, I like to run a softer spring. But thats me. some people like the firmer feel of the stiffer one.

Most tuners agree that there should be some free sag, so you don't top out the shock needlessly. The standard should be no less than 1/2" free sag. However, maximum free sag should be approx 1". Not everyone agrees on this number though. some say it can be as much as 1 1/2". I personally don't have a problem with this number, though my "magic" free sag number is 3/4'', though it usually ends up right about 1".

If you do have more than 1 1/2", you should look at a softer spring.

 

[shockdoc]

.47 up frt. & 5.1 or 5.2 in back at 225 lbs. will definatly not work. That is out of balance before you even sit on it.



doc

 

[Science]

Thanks for the info.
I'll try the 5.4 & see how that works. Fortunately, I already have one! It's weird that both RT's & Wilkey's site call for the 5.2.
If any one else has any info, please feel free...

 

[steve125]

It's also possible that what you think is a 5.2 may test closer to a 5.1. I've had 2 RT springs tested here recently and they have varied a bit. One rated as a 5.0 was tested as a 5.08 and another rated at 4.8 was a 4.75. Having your springs tested is the best way to know for sure. :thumb: