Midvalve float

JTT

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#1
I have been toying with midvalve float on an '01 CR250 (Showas). To try to eliminate the placebo effect, I have enlisted the help of a local Pro rider. Here's my question.... After lessening the float, increasing float and trying stock float, he has indicated that there was little difference? Is this due to the fact that the midvalve to basevalve ratio is so low on the Showas (something like 2.5:1 as I remember)?:think
 
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#2
Servus JTT,

Could you provide some numbers: cartridge diameter, rod diameter, what exactly did you change on the midvalve, MV float!

Michael
 

JTT

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#3
Sorry, let me clarify...
Showa twin chamber ("01 CR250)
23mm cartridge, 12mm rod
Revalve done by local company (reputable)
Midvalve shims changed slightly as result of revalve to decrease base (smaller shims), but slight increase in initial part of stack (larger shims).
Float level stayed stock.

Still somewhat harsh and with inquisitive nature I decided to do some experimenting. I then decreased float by .6mm = slight change, slightly firmer, but only very slgiht, then increased float by .4mm = very little, if any change.

Hope this is a little clearer. I was reluctant to post actual valving so as to not offend Jer or any other Professional tuners, hope I haven't stepped on any toes :eek:
 

AAT

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#4
I have found that mid valve on the rebound piston assembly on '99 to 01 CR 250's should be turned into a check valve for most average riders (because it ceates a small amount of compression dampening).

Remove all the shims on the compression side and replace with one .035 thick shim so that the mid valve acts as a check valve only.

Also if you are not as fast as the local pro you were talking with, his settings which may be perfect for him, will be horrid for you.

After turning the mid valve into a check valve, ride the bike and determine if the compression stack needs to be modified to improve your ride.

What is your wieght and are the springs correct?

Why would it offend someone to use specific numbers?
How can the sport grow if things are kept a secret. Look at all the information Race Tech provides.
 
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#5
Servus JTT,

Two things come to my mind:

Basically I'm with AAT that it is a big NoNo to let somebody else rate YOUR suspension; even if it is for comparison purposes! To my understanding the suspension has been revalved for you, so even if it might be perfect for you and your style, the pro rider will not be able to judge it. It doesn't make a difference for him if it bottoms very hard, a little less hard or medium hard! For you it might be a day and night difference!

Second, I increased MV float about the same as you did and it made a big difference. So, if your MV float height is not really far from the optimal working point this may be a sign that the problem lies somewhere else.

Again I can't emphasize enough how big a difference the video taping makes. It takes so much guess work (there is still plenty left though ;)) out of the process of suspension tuning and it helps you from listening to much to your feelings which can be very deceiving. Been there, done that :eek:

Michael
 

JTT

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#6
Thanks Guys for your input. Just for clarification...this is not my bike. I am trying to learn about suspension. The revalve referred to was done for him in particular, on his forks, although coincidentally, when mine were done by the same tuner, the stacks were indentical :think

ATT, thanks, but I am a believer that the midvalve system was designed and installed for a reason...what that reason is, I don't yet know ;) . so therefore would like to learn to work with it, instead of just removing it.

Drehwurm, I understood from you previous posts that the change in yours was dramatic, this is why I was somewhat surprised to see minimal effect. I was wondering if it might have anything to do with the fact that your system, with, what I believe is a larger cartridge and therefore greater midvalve:basevalve ratio (I remember something in the 4:1 range?), amplified the effect more so than on my setup with a relatively low ratio (approx 2.5:1).