Spring rate for weight 2k5 yz250 2t 230lbs

[Dynamic]

So I got a new to me bike this year. 2005 yz250 2 stroke with ~30 hours on it. (came with the original topend kit and previous owner was known). I've been riding the heck out of it and have started hitting some jumps.

Took the time to try and adjust my sag. When my race sag is at 100mm I have no static sag at all cause I have to seriously compress the stock spring. Stock spring rates on the 2k5 are .44 fork and 4.9 shock.

So went to yamaha and ordered some new springs today. I ordered .48 fork and 5.4 shock. Right now I weigh ~235lbs probably 240-245 with full gear.

Now that the backgrounds done I have a few questions while I wait for parts.

Do those new spring rate numbers seem right for my weight?

Is the change in SR going to be a noticeable improvement?

Is it worth the $150 the shop wants to put the fork springs in? I have the money, doing it myself would learn me up on my shock, but I'd be pissed if I screwed it up, and I don't have a shock driver. I'll do the back myself cause thats EASY.

Edited May 4, 2011 by Dynamic

[RCannon]

I believe I woudl change my own fork springs....maybe 50 for the springs woudl be a reasonable change, btu 150 is a lot. You can do it if you follow instructions.

[bg10459]

The fork springs sound good, but I'd guess you're at least one rate too light on the shock.

I agree w/ RC, $150 is too much to change springs. If they include HQ oil; maybe ?

[FRECNDY]

If you back off your preload to get at least some static sag, you can use the difference between that and the race sag to calculate the approximate spring rate required to achieve your target difference. Of course, the non-linearity of the linkage will come into play a little bit, but it is your best option, AFAIK.

On the front, since there's no preload adjustment apart from the shims, you can do the same, and it should be pretty linear.

If I remember right, the '05 still has the older forks like my '02. If so, changing the springs (if that's all your're doing) is dead simple, and can be done with a bit of extra care (you have to open and close them both together, not one at a time) with the forks still in the clamps (upper clamps must be loosened) and the wheel on. Of course, it's best to at least change the oil while you're in there if you're not just swapping back and forth between a bunch of different spring rates with recently overhauled forks, which means pulling everything apart. It's pretty simple to do an oil change if you don't need to change the seals, and you don't need any special tools.

Find my link in this forum to the European site with free printable manuals.

[mstyer]

I'm the same weight as you. My suspension shop installed .45 springs in the fork and a Ti 5.3 spring in the rear. I race hare scrambles, so the higher numbers sound about right for you doing MX. You may find the fork a bit stiff, but check your preload to be sure.

Changing the springs yourself is a piece of cake. If you can change the oil on your car, you can change fork and shock springs. You do have a manual, right?

[Dynamic]

Yeah I do have a manual, I also have a internet connected computer in my garage for videos and such (super useful for looking stuff up while working on the bike).

The 05 has the SSS fork. They went to the KYB in 06.

The $150 is all inclusive and does include shock oil. You guys have me thinking I can do it myself now. I've been watching a number of videos on how to change fork springs and there are a few "specialty" tools that I wonder if you guys have some homebrew solutions for.

The seal driver I could probably make out of some PVC pipe or any pipe that has an inner diameter the same as the outer diameter of the fork. Maybe?

A tool to hold the spring compressed while I undo the top bolt. I could probably use a case of beer to have a buddy hold it down while I undo it.

Fork bullet (to let the seals past the square ridge for the bushing)....I don't know what the best method for doing this without the bullet is. All the videos use the bullet.

I've been watching the videos, and it doesn't look like there are two many surprises inside. Anything I should be particularly careful of when I do this, mistakes you've made for me to avoid?

[kan3]

The 05 has the SSS fork. They went to the KYB in 06.

The YZ uses a KYB fork

The 05 uses the AOSS and the 06+ has the SSS forks

A tool to hold the spring compressed while I undo the top bolt. I could probably use a case of beer to have a buddy hold it down while I undo it.

If by "top bolt" you mean the cartridge then you're thinking of open chamber forks. You don't need to put pressure on the fork to remove the cartridge or rebound adjuster at the bottom.

Fork bullet (to let the seals past the square ridge for the bushing)....I don't know what the best method for doing this without the bullet is. All the videos use the bullet.

I use a shock bullet for a shock seal head but just use a baggy covered in wd40 for fork seals.

Technically, the only special tool that you'll need on 05+ forks is the tool to remove the compression assembly from the cartridge.

[mstyer]

Are the AOSS forks that different from my older open bath ones? All I have to do to change springs is remove the top cap and they lift right out of the top.

For the shock, remove it from the bike, loosen the preload ring, and the cup at the bottom should pop off allowing the spring to slide off.

[ajd187]

I'm the same weight as you and I use those springs. They seem to work just fine. One note, you will probably want to back off your compression and rebound with these new springs. The stock settings are way too stiff with the correct spring for your weight IMO.

You don't need a fork seal bullet or seal driver to do the fork springs. All you need is the cap wrench for the top cap. This:

http://bit.ly/jEtuw1

And really you only need the long piece to take the outer cap off to do the springs, although if you have the forks apart you might as well change all the oil anyway.

$150 is way too expensive to have a shop do it IMHO. It's an hour job for them tops.

[kan3]

They're probably charging him for a rebuild on the forks and a $150 is about right assuming it comes with wear parts.

[BDubb106]

I weigh 225 and I run .49 fork springs and 5.4 shock spring on my MX race bike, but I also installed the Type 2 gold valve kits from racetech. They are designed for supercross and taller/ bigger riders and seems to help stiffen things up quite a bit which is how I like my bike, I give up a little in the corners to be able to be able to be overly aggresive in the really rough stuff and whoops at speed.

My set up sucks for woods or casual riding though, WAYYYY too stiff to ride at any good pace in the stick, so be careful how you set it up depending on what terrain and how hard you plan on riding

[Dynamic]

I weigh 225 and I run .49 fork springs and 5.4 shock spring on my MX race bike, but I also installed the Type 2 gold valve kits from racetech. They are designed for supercross and taller/ bigger riders and seems to help stiffen things up quite a bit which is how I like my bike, I give up a little in the corners to be able to be able to be overly aggresive in the really rough stuff and whoops at speed.

My set up sucks for woods or casual riding though, WAYYYY too stiff to ride at any good pace in the stick, so be careful how you set it up depending on what terrain and how hard you plan on riding

Thanks that was very useful. I too prefer suspension to be a little stiff...I'm not doing enduro cross, thats for sure. Most the trails around here are pretty smooth and well ridden. Getting into more track and jumps though.

[BDubb106]

Youll def benefit from the type 2 gold valves then as they provide a little extra bottoming resistance and overall smoother operation for us bigger/ taller riders. Something to look into while you have the suspesion torn apart. Also note I had to go with factory connection fork springs because they are the only ones that had the .49 springs in stock. I experimented with too many suspension set ups to count before I found one that actually suited my needs and style. Its def. a timely process if your setting it up on your own. If you dont ride super aggresive on the track you can get away with a type 1 gold valve kit but for the same price you can have the type 2 and it will benefit you more as you gain confidence and speed on the track and start to push harder. Doesnt look like race tech offers a .49 fork spring for your bike so youll have to decide whether you would rather use the .48 or the .50. I tried both and decided I needed the .49 to keep the front end from wanting to push as it did with the .50 fork springs.

Hopefully that makes sense because I might have confused myself a little with the all the numbers.

If something doesnt make sense Ill try to clear it up as best I can.?

[Dynamic]

It does make sense and I am a tall rider (6'3). What I think I will do is try just the springs for now....see if I like the SR....then in the off season when I will service my fork anyway, I will re-evaluate the SR, change the valves to the RT Gold T2, replace the seals as I am intending on re-using my seals this time.