Midvalve question for the suspension guys

Miedosoracing · Jun 17, 2005

Well, I am gonna redo my midvalve. I am pretty happy with the forks, but looking for a little more plushness. I think I am gonna stick with my base valve settings. Questions I have are this.
Honda doesn't seem to run bleeder shims (on some that is, why not)

GV's don't use them at all, they use the blowoff valve

and what do you prefer, a decreasing size stack on the midvalve, or two staged or blowoff?

WhiPit · Jun 18, 2005

PLEASE DON'T GO THE RT WAY!!! Your bike REQUIRES a mid-valve!!
What kind of riding are you doing? And the trick isn't completely in the "type" of stack as much as it is in the amount of "float" the stack has.
It's good that you're thinking mid-valve (which needs some tweeking on the '05 CRF450), but there are some changes that can be made to the compression stack as well.

Miedosoracing · Jun 18, 2005

sorry, I didn't clarify myself on which bike I am working on. It is the 03 KX250, my gineapig bike. I have already done things on the compression stack a couple of times to get it where it is now. I am looking further now, and want to know more about the mid valve. Ross and Enzo told me that he has found more gain working on the midvalve in some cases than the compression stack. Ok, so explain what you mean when you say float. do I want a certain amount of oil to just blow through, up to a high velocity, where the shims would come into play?

bclapham · Jun 18, 2005

do a search on "midvalve" or "mid valve"

as for "float", or lift, the midvalve is setup like a check plate inthat its shims IDs are bigger than the rebound and they move up and down on a post with a spring at the back. you need to think in terms of port size, as the stack "lifts" of the piston face and flows and then they will bend and flow yet more oil.

a low lift mid, enables a plush fork that isnt mushy, but you will have to tune with both the base and mid.

that said, time to get twin chambers if you want to learn suspension, you wont see much more of the non twinnies on new bikes.

Miedosoracing · Jun 18, 2005

Thanks Bruce, that helps me understand a lot more. Yeah, I know the twins are coming the twins are coming :-) , but I also am about to get rid of this bike, so I am doing my dumby testing right now. That way when I get into my new Honda's forks, I don't totally mess them up.

KTM-Lew · Jun 18, 2005

I don't think the 03 KX fork has a spring on the mid-valve? Didn't they use an o-ring to preload it? Much to be gained with mid-valve mods on those.

marcusgunby · Jun 18, 2005

The 03 has a spring, the cr125 and older kx fork(46mm) used the o ring.

KTM-Lew · Jun 18, 2005

Marcus

OK. I wasn't sure when they changed. The 03 have 48mm tubes? Does it have the same type of rebound piston as the Yamaha ie; two piece?

marcusgunby · Jun 19, 2005

Yes the 03 was the first year of the big tubes, they dont have the same pistons as the yam, also in 04 or 05 the went to a removable cartridge rod-ie no peens etc so its much nicer to work on, the 03 you had to really heat them to open up the cart.

KTM-Lew · Jun 19, 2005

Thanks Marcus, been hanging with the KTM guys for awhile. Kind of lost track on the jap bikes.

Midvalve question for the suspension guys

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