250 yz shim stack

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Rcannon

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Nov 17, 2001
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I tried the stock .43's, .44's and 46's in my 97 YZ 250. This bike uses almost identical valving as the 99. They helped a little bit, but handling suffered.

You can try the valving changes talked about for close to nothing. New springs are 80.00.

I say go with the valving . You'll be happier in the end.
 
K

KTM-Lew

Member
Jan 26, 2002
428
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renes said:
I'm confused. Are you talked to me or F_Red?
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I think he's talking to himself! :nener:

He was talking to Fred I believe.

Do these have any kind of preload spacers? If they have a long spacer then he could use a set of springs out of the 00-02 WP forks. The 4-strokes came stock with .42's (EXC & MXC) & .44's (SX) and are 30mm longer than the stock 94 Yamaha. If they have long enough spacers to cut down he may find a set of springs for cheap! :nod:
 
F

f_red

Member
Jun 22, 2005
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hi, i weight 75Kg fully dressed! Can you tell me which spring i should use? It may be the first point to be controled!
 
F

f_red

Member
Jun 22, 2005
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How can i see if it is a 0.41 or a 0.42 may i mesure it or it is written somewhere?
 
R

Rcannon

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Nov 17, 2001
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Heck, I was talking to everybody with crappy YZ forks. I am excited to finally have them fixed.

My only point was that the spring changes do not really fix the yz forks.
 
R

renes

Member
Apr 7, 2002
35
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f_red said:
How can i see if it is a 0.41 or a 0.42 may i mesure it or it is written somewhere?
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Race Tech has a pretty good spring rate calculator. But you seem to be in the right range with a 0.41 or a 0.42 (You can also try one of each). I've read in my yamaha manual that there are little grooves at the top of the springs where they are flat. These grooves are supposed to tell the spring rate. None of mine have these grooves. If you look on the internet you can find formulas for figureing out your spring rate. You just have to measure the wire gauge, spring outer diameter, and number of active coils.

All the top suspension tuners will tell you that getting the right spring rate is the very first thing you must do to properly setup your suspension. You can have the very best valving in the world, but if the suspension is not sitting in the proper position of the stroke, it won't work like it was designed to work. Good luck.
 
K

KTM-Lew

Member
Jan 26, 2002
428
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Rcannon

You have made it abundantly clear that Miedoso has made all your dreams come clear. Fred is across the pond and is riding a completely different bike from yours. Is it possible his bike needs different mods than yours did?

Fred

The WP springs are not marked. If you can find someone that has owned a 00-02 KTM and ask if they have the stock springs you may find what you need. The EXC/MXC 200 used .38, 250/300/380 used .40, RFS .42. The SX models used .42 & .44. You need to find a shop that can test the springs allthough fork springs are tough to test accurately. You just need to compare one to another. You may even find a set at the KTM shop? The stock springs out of the 98-99 Marzocchi would fit, with appropriate preload spacer mods, and are .45 stock. You could use 1 of those with 1 of the stockers.

Don't be afraid to use a stock spring with a stiffer spring to average the rate.

While this may seem a convoluted way to get springs the part # that "fits" your bike doesn't fit anything else. Hate to see you buy new springs if you don't have to.

Does anyone know how long a preload spacer these use stock?
 
R

Rcannon

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Nov 17, 2001
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R

Rcannon

~SPONSOR~
Nov 17, 2001
1,886
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renes said:
:bang: Thats a pretty generic comment.
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The comment was a bit generic. I should have said in my case the spring changes did not do much or me.

Did it help your 99 yz forks???
 
R

renes

Member
Apr 7, 2002
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I do have to admit that the spring changes on my 99 did not effect the forks as much as they did on the 94. My 99's already had stif springs. I only went up a small amount in spring rate. The 94's stock spring rate was really low though. The forks on my 94 and my 99 are very different in feel. It is hard to compare them. I also recently put in gold valves. I'm not so certain that was the best move. I probably could have come up with my own stack if I had more patience. But the GV's gave me a good starting point. Someday I will go back to stock pistons. And I also think I too will start with 4- 24's in the low. I'm not sure after that though. I think the mid is where I should be spending most of my time and effort.
 
K

KTM-Lew

Member
Jan 26, 2002
428
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Rcannon

The 94 forks are quite a bit different than the 96 & up forks. I allways rec the correct springs for a riders weight. His valving is likely too soft and with the soft springs it's riding way low in the stroke.

Sorry if I hurt your tender feelings? :p :cool:
 
R

Rcannon

~SPONSOR~
Nov 17, 2001
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Lew, no big deal...I was just surprised. Your always the first person helping others on the forum and I appreciate all that I have learned from you.
I love reading the suspension threads and everyones comments.
 
S

stimps

Member
Jun 25, 2003
34
0
Just want to thank Ktm-Lew for for his help and willingness to help me out on my 2000 YZ 250 forks :cool: . I have modded my midvalve in line with the suggestions and am looking forward to trying them out. I think the hardest thing is finding good info on what part of the suspension effects the different responses. Eg Shim thickness, Diameter, part of the stack, midvalve lift etc. Having stripped them right down it makes you realise that the base valve is literally only half the equation. I'm gonna order some more shims so I have some more options to try.Thanks for all the help.
 
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renes

Member
Apr 7, 2002
35
0
stimps said:
I have modded my midvalve in line with the suggestions and am looking forward to trying them out.
Click to expand...

Why don't you share what mods you did to your midvalve. I've been playing around with mine for a couple months now. I'm not sure that I'm actually getting anywhere with it.
 
W

WWR

Sponsoring Member
Jul 15, 2000
161
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I've been playing around with mine for a couple months now. I'm not sure that I'm actually getting anywhere with it.
Click to expand...

Same here. Anyone have a solid recommendation for this?
 
M

Miedosoracing

Member
Feb 22, 2005
79
0
I'm gonna chime in here, but I am sure many, many of the tuners will disagree. I was told I don't deal with the midvalve, which is incorrect actually in some ways. I am working on a torque calculator that will let you put in the values and come out with a closer setup than the current types available. I believe the midvalve should be considered in somewhat these terms. Starting at a 20-25% (the stiffer you make it the less initial value) value of the initial part of the stroke decreasing to 10% max value. Meaning, if you take out the midvavle shims and left them blank, you would see a big difference in your initial sag. You would droop all over the place. If you put in the blowoff type valve, you have the initial hold, but when it gets to deeper parts of the stroke, you will see a decreasing amount of effectiveness. That is why I believe GV's don't require the midvalve as normal. They are focusing only on the first part of the stroke, then the blowoff goes open gradually, and you have max of about 10% again. If you design your midvalves with that in mind, you will see that I may be off alittle in the %'s but pretty acurate in what it does. I am not saying you don't want to use the midvalve, but use it on a weighted basis of how you make changes. I personally believe the midvalve is a fine tuning part of the suspension. Make it almost perfect with the compression system, and then make minor changes with what you want to gain with the midvalve.

Now, that being said. Let me get my az chewing. I know it is coming :pissed:
 
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