I'm trying to get a thread started where we analyze a valve stack

[Jusa]

to add to others comments, i feel we as normal riders feel bleed effect from the low speed and cross over stacks mostly(same as Jarkko said) 90% of all the riding we do is the low speed stack (taking into account how it contacts the hs) the hs stack i and others have actually done away with completely(with a slightly stiffer low speed stack) and it really doesnt ride much different.

I don't totally agree this because every time I make the new settings for me, I usually make changes to the hs stack (for MX use) for example this:

250 yzf -09

std

40-0.25 (7)

36-0.15

30-0.15

40-0.25

38-0.25

36-0.25

34-0.25

32-0.25

30-0.25

28-0.25

26-0.25

24-0.25

22-0.25

mod

40-0.25 (7)

36-0.15

30-0.15

40-0.25

38-0.25

36-0.25

34-0.25

32-0.25

30-0.25

28-0.25

26-0.3

24-0.3

23-0.3

I really feel the difference with this stack. I also change cross overs in some applications, it depends...

I have also tested ls stack mods with -09 450 yzf

std

40-0.2 (6)

36-0.15

30-0.15

40-0.3

38-0.3

36-0.3

34-0.3

32-0.3

30-0.25

28-0.25

26-0.3

24-0.3

mod

40-0.2 (8)

36-0.15

30-0.15

40-0.3

38-0.3

36-0.3

34-0.3

32-0.3

30-0.25

28-0.25

26-0.3

24-0.3

Not good! It went side to side and also kicked hard. This stack didn't allow the rear to travel enough. It wasn't good either when I raised the fork.

Edited February 14, 2010 by Jusa

[455]

It might have been better with the first cross a 36.1 then the 2nd a 34.1.

When I do a 3 stage I keep the cross thicknesses at .1's no thicker.

[mog]

I don't totally agree this because every time I make the new settings for me, I usually make changes to the hs stack (for MX use) for example this:

250 yzf -09

std

40-0.25 (7)

36-0.15

30-0.15

40-0.25

38-0.25

36-0.25

34-0.25

32-0.25

30-0.25

28-0.25

26-0.25

24-0.25

22-0.25

mod

40-0.25 (7)

36-0.15

30-0.15

40-0.25

38-0.25

36-0.25

34-0.25

32-0.25

30-0.25

28-0.25

26-0.3

24-0.3

23-0.3

I really feel the difference with this stack. I also change cross overs in some applications, it depends...

I have also tested ls stack mods with -09 450 yzf

std

40-0.25 (6)

36-0.15

30-0.15

40-0.3

38-0.3

36-0.3

34-0.3

32-0.3

30-0.25

28-0.25

26-0.3

24-0.3

mod

40-0.25 (8)

36-0.15

30-0.15

40-0.3

38-0.3

36-0.3

34-0.3

32-0.3

30-0.25

28-0.25

26-0.3

24-0.3

Not good! It went side to side and also kicked hard. This stack didn't allow the rear to travel enough. It wasn't good either when I raised the fork.

IMO you are feeling the 23 clamp on the yzf 250 more than the hs, you are just adding damping overall.It would have been interesting if you had kept the clamp the same, i dont think it would have been a noticable change in that case.

on the 450 stack again you have raised damping but just beyond what you are comfortable with.

[mog]

It might have been better with the first cross a 36.1 then the 2nd a 34.1.

When I do a 3 stage I keep the cross thicknesses at .1's no thicker.

Yes i believe it maybe better done that way, its not a stack i have used in others bikes to be honest.

[shockdoc]

mod

40-0.25 (8)

36-0.15

30-0.15

40-0.3

38-0.3

36-0.3

34-0.3

32-0.3

30-0.25

28-0.25

26-0.3

24-0.3

Not good! It went side to side and also kicked hard. This stack didn't allow the rear to travel enough. It wasn't good either when I raised the fork.

Wouldn't it been better to lower the fork? Since its stiffer lowering the forks would help compress the rear better??

doc

[kevinstillwell]

your % difference column reads differently to the numbers you give?

% diff can be figured different ways, depending on which way you divide.

Using the low speed numbers for example:

76 / 112 = .68, but that's not to say it's 68% softer. That means 112 x .68 = 76. It is actually 32% softer. Most would then say that 112 * .32 = 36 lbs softer, which is 112 - 36 = 76.

112 / 76 = 1.47, and that does mean it's 47% stiffer as 76 * 1.47 = 112.

Confusing huh.

It's best just to play with a calculator to get a feel for it.

[Jusa]

Wouldn't it been better to lower the fork? Since its stiffer lowering the forks would help compress the rear better??

doc

I mean raising the fork=lower the fork legs in triple clamps

[mog]

% diff can be figured different ways, depending on which way you divide.

Using the low speed numbers for example:

76 / 112 = .68, but that's not to say it's 68% softer. That means 112 x .68 = 76. It is actually 32% softer. Most would then say that 112 * .32 = 36 lbs softer, which is 112 - 36 = 76.

112 / 76 = 1.47, and that does mean it's 47% stiffer as 76 * 1.47 = 112.

Confusing huh.

It's best just to play with a calculator to get a feel for it.

OK we need that baseline any decent std dyno run would do to be honest, but most of use feel the yzf hits the mark closest std.

[kevinstillwell]

kevin without giving too much away, how does a std 07 yzf 250 compare to say the std rmz and mine? thats what we need now,a good base line.

That would probably be giving away to much,

Edited February 17, 2010 by kevinstillwell

[kevinstillwell]

any decent std dyno run would do to be honest

Ok, I've reconsidered. Below is the stock dyno run for the RM 85 shock.

[mog]

i am amazed how stiff a 85 shock is, i never thought it would be....

i dont think its giving a lot away to show a 06/07 yzf shock, you have shown a 07 rmz std, without something else to compare it to, its just talk for the sake of it,

one thing thats interesting is everyone rightly said my stack is softer than std, but no one thought it would loose a lot more low speed than high speed(the high speed retains a surprising amount of damping IMO), so we have learnt that its all guess work at a level without a dyno.

[racerfmx450]

The stack is actually considerably softer all the way thru. Just look at the numbers.

- at low speed, your stack is 36 lbs softer, or 32% softer

- at mid speed, your stack is 127 lbs softer, or 23% softer

- at high speed, your stack is 191 lbs softer, or 19% softer

That is a bunch, considering the comp adjuster might change the low speed 5% and the high speed 1%.

19-32% Softer then a stock Rmz-250 Stack?!

and not way to soft?

it"s hard to believe !

calculated OK, a softer stack has much less Kavitation and feels not so soft on Shocks.

[shockdoc]

i am amazed how stiff a 85 shock is, i never thought it would be....

.

The RM is the stiffest I feel. Esp. with their stk. linkage.

doc

[mog]

The stack is actually considerably softer all the way thru. Just look at the numbers.

- at low speed, your stack is 36 lbs softer, or 32% softer

- at mid speed, your stack is 127 lbs softer, or 23% softer

- at high speed, your stack is 191 lbs softer, or 19% softer

That is a bunch, considering the comp adjuster might change the low speed 5% and the high speed 1%.

19-32% Softer then a stock Rmz-250 Stack?!

and not way to soft?

it"s hard to believe !

calculated OK, a softer stack has much less Kavitation and feels not so soft on Shocks.

🤣

it would be very interesting to see a 07 kxf 450 shock with its 0.15mm face shims in comparison

[kevinstillwell]

it would be very interesting to see a 07 kxf 450 shock with its 0.15mm face shims in comparison

OK, here is the 08 KXF 450 stock shock dyno curve.

[racerfmx450]

it would be very interesting to see a 07 kxf 450 shock with its 0.15mm face shims in comparison

:thumbsup:also!

the kxf 450/07 has a soft shock-valving but only 0,25 Transmission-gap:thumbsup:

[mog]

hmm this is very cool, we can see the kxf 450 has a similar mid and high to a std rmz 250, but a softer low speed.

[kevinstillwell]

And here is how it compares to Mog's 3 stage stack.

My the way, how do you pronounce 'Mog'? Is it "o" like frog or toad.

[kevinstillwell]

And here is how the stk 08 XKF 450 compares to the 07 RMZ 250.

[mog]

I pronounce it Marcus

mog is like the cat moggy, not sure why i signed up with mog to be honest.

Its interesting how the kxf 450 and rmz 250 std are so close from mid and high speed, yet very different at low speed.Is that a characteristic of the kyb vs the showa, or the 0.15mm shims in the 450?