Talked to my local suspension guy, midvalves

Questions and comments about converting to beefier forks..
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strider80
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Talked to my local suspension guy, midvalves

Post by strider80 »

I talked to my local suspension guy today (http://www.moto-pro.com) about getting my 2001 KX125 front end revalved next year. He said that his typical base valve kit would work well, and then replace the midvalve with a check plate kit and leave the bladders intact.

He said the forks will work well with a check plate with the bladders, what do you guys think? He said he has done this job on lots and lots of USD KYBs for the woods and they work really well. I have not heard anything about his work on my particular forks, but have heard great things about his work in general.

Should I consider a national shop instead? I have also considered Factory Connection, Enzo and MX-tech, but kind of want to use a local shop. Moto-pro also allows for free reshimming for 30 days after the work is done.
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Post by Green Hornet »

My guy did the same thing. Left the bladders, made a check valve out of the mid-valve & utilized shims/added-subtracted from areas of the forks. He says this is what he uses for Woods Bike Application. Mine feel fine & work fine.
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Post by bradf »

Well I'll tell ya what I think. There is a world of opinions on this subject from the big boys and the little boys. The one thing that always had me baffled is why would you eliminate a MV with a check plate? So I asked FC, MX-Tech, Race Tech, Pro Action, and the ol bum that lives in the van down by the river. There was one common thread amongst all of them and that was that the mid-stroke harshness was too severe as is. I went out to MTF (Millsaps Training Facility) and talked to the big boy mech Jim West out there and he remembered the bladders well. He hated them. They didn't last long. But he fixed his with another set of forks. Here is what I learned:

Living in a van down by the river really sucks.

Mid-valves were a technological step up, an advancement in fork design in that they provided true HS dampening vs the old fashioned digressive (check-plate) system.

Bladders were an attempt to control bottoming on hard landings for the big boys that race SX/MX.

Simply removing the bladders was not enough in that there were other pieces to the equation, like the hardware directly above the bladder, the restrictive barrier which includes the machined washer that sits under the spring. This has a function with or without the bladder.

Why did some suspension experts differ in opinions so much? Because some had tried ways that proved ineffective and stopped there. Some tried ways that helped a little and stopped there. And some possessed a great deal of suspension knowledge and did so much testing and trial and error that they found the holy grail.

Anyone can make the bladder forks work better pretty easily. But keeping the MV is the key. Simply removing the MV and replacing it with a CV will help but it won’t get you where I am. There is so much interaction of the parts that for every tweak on one affects the others.

So allow me to come right out and say that only Jeremy at MX-Tech hit it on the head. Not only did I remove the bladder, but I removed the hardware above it. But Wait! If you call right now…I’ll tell ya more for free!

The BV needs to have all but 4 of the 24’s removed. This will help a lot on the LSC that we trail riders spend much of our time in but it will allow more oil flow on the HS. So let’s go up to HS and take a look.

HSC is controlled mostly, MOSTLY, by the MV. But what about that washer of the RB that sits under the spring? It’s still there doing its restrictive stuff. And what about the bleeder shim right behind the piston on the MV side? Did you even know it was there? Did you know what its special purpose is/was? Simply removing the MV entirely and replacing it with a CV will make an improvement. But it aint the best. Ya gotta do something with the RB washer. It can be removed entirely and that will work but then the spring will rest right on top of plastic with holes and gouge the pee pee out of it. You could drill holes in the washer but then the spring would cover the holes. Or you could do what I did. Jeremy loved this idea. I ground 5 deep grooves in the outside edges of the washer past half way through. I used a bench grinder so the notches were fairly wide, and deep. Now the spring still rests on the metal washer but won’t gouge the plastic but oil flows freely past.

And remember the bleeder shim? If it were left in as many many experts overlooked, it would allow the suspension to shoot through the first half of travel and then there would be a “Bottoming” issue. The same issue that the bladder was there to keep from happening. Soooo, remove the stinking bleeder shim!

Here’s what you end up with:
Bladder is gone
RB modified
BV all but 4 of the 24’s removed
Bleeder on the MV gone
Oil level NOT 85 mm but now 120 mm. = Less bottoming resistance, but when we get to the top of the stroke we still have fairly plush feel vs hydro lock. This what GNCC and us lowly trail riders want.

It’s all a matter of knowing what interacts with what and making the BEST out of what you have. The BEST is a fully functioning MV that allows the shims to control HSC vs a simple CV.

It didn’t take much to make my forks SA-WEET! Jeremy’s input on the bleeder and my idea on the RB along with the bladder removal was very sim-pull. So easy a cave man did it! I have had a few experienced GNCC riders take a spin and they loved it. One lives in Travelers Rest, SC. I did not know who he was until 2 weeks later. When a suspension can eat the sharp choppy rocks and roots and still take hard high speed hits (severe whoops) you have a real working set-up. Thank you MV! And of course Jeremy. And the old bum that lives in the van down by the river.
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Post by Green Hornet »

Tell us more about the old bum that lives in the van down by the river

:grin:
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Post by IdahoCharley »

Good write-up Bradf.

I've played with MV set-ups and do like the progressive feel that they can offer. I personnally think that for really fast riders the MV can offer more control but for home tuners getting the set-up right for a given terrian and rider will have the home tuner taking his forks completely down at least ten times to get the MV/RB portion of the suspension dialed in. It really depends on rider ability, how much time he wants to put into his forks, and terrian IMO on whether or not the MV hassel is worth it. A MV which is set-up to work well for trail riding will also fatigue the related shims pretty fast also which will have you rebuilding the shim stacks alot more than if you run a CV.

A CV system will likely satisfy the majority of trail riders and its certainly easier to maintain longterm and just adjust the suspesnion action with oil level, visocity and base compression valve stack. Gets you 90% of the way there IMO. Just my .02 and you get what you paid for.
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Post by Indawoods »

Let me tell you... the clicking MV drives me nuts!!!!!

If the KDX wasn't so quiet it probably wouldn't be an issue... but I can hear that damn thing evertime I come down. I think I can feel it too.... :neutral:
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Post by IdahoCharley »

The MV should not be clicking IndaW. I can't even think about how it would click to be truthful. It should be in oil.
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Post by bradf »

IC you hit it right on the ol noggin. The simple and easy way is the CV and it will satisfy the vast majority of weekend riders. I did a bunch of home work because I didn't want to tear em down and test and tear em down again. My driving factor was that not only do I ride trail conditions but I ride fast whoops a lot. I need/must have a broader capacity from the forks. That too is the reason for my Showa shock. But if anyone has 01's and possibly 00's-02's, it is easy to make them like mine with my set-up which I will e-mail. I came close to doing a MV conversion but I am very glad I did not.

The old bum that lives in the van down by the river told me that with all the money we spend on bikes we could surely have bought a custom van with 8 track tape, Craig Power Play speakers, black light and water bed in the back.
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Post by IdahoCharley »

The old bum has it good - if he said he could have or should have bout a custom van with an 8 track tape player he surely has a 4 track player which everyone knows is more rare and sought after than the 8 track players. :lol: :lol:
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Post by KDXer »

I have 02 forks with Gold Valves and .38 Racetech's. The MV has been changed with a 'midvalve replacement kit' (whatever that is, guessing check plate config). I'd be very interested in what settings/shims/M/V config you would suggest for me. I am in the process of getting the 04 KX shock so my bike will be going to the Racetech tuner to get the front and rear dialed in correctly when it arrives.

Thanks for sharing this great info Brad. :partyman:
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Post by bradf »

From the "what I have been told" files:
Race Tech uses a "unique" approach to tuning. The Gold Valve is an example. I have heard that the Gold Valve has significantly different flow rate than a stock piston which is probably good when used with their shim stack recommendations. If the MV piston is designed to work without a shim stack and use a CV instead then it probably won't work well with a MV stack. It is the "progressive" vs "digressive" principal and what works with what. When I talked to all the different suspension sperts, ex and current, I asked specific questions pertaining to making the best GNCC type suspension with the MV stack because I knew it could be done but I didn’t know what the Holy Grail was. I did know there was Grail cuz I saw it shining over the castle Anthrax. My quest was to find the Grail. Race Tech May have a good BV set-up but for bladder forks but they told me they needed to eliminate the MV stack and convert to a CV which I refused to do. This was also the same word I got from the other shops, except one in Florida that would work with me to eliminate the bladder and maintain the MV stack if I needed to re-shim and re-shim and go through all that testing. They had a secret of their own but wanted $450 to do it themselves, which I really can’t blame them. But I am not a racer and know body uses these anymore so it wasn’t like it was going to win some national championship. But it was their Grail and it was worth something. That’s when I talked to John Curea at MX-Tech and then on to Jeremy. My set-up uses the stock piston on both the BV and the MV and doesn’t cost anything other than a re-build kit and a RB mod. So I found the Grail and it was MX-Tech.
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Post by strider80 »

So MX-tech just modded the stock components, so aftermarket piston kit? May I ask what he charges for a custom setup like that?
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Post by bradf »

I did all the rebuild and mods myself. I replaced a couple of shims that were not flat. MX-Tech gave me the scoop on the bleeder shim and why, the BV stack, the oil level, and that I needed to either get rid of the RB or allow oil to flow past. The RB mod of grinding large slots was my idea. The secret was not complicated. MX-Tech new how to keep the MV progressive stack and eliminate the bladder and keep the fork from shooting through the first half of travel. Basically they knew how to turn the MX/SX designed fork into a GNCC/woods fork. I got what I was looking for. Now I am dealing with a set of 03 YZ250 forks on my buddy’s bike. It has a mid-stroke spike that hurts and is so harsh I get arm pump standing next to it. I don't know the grail on making these woods ready. I am trying to talk him in to sending them in. He didn't ever like the feel and after he rode mine he is disgusted with the feel.
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Post by strider80 »

So Brad, is there a full write up in the future for us, or is most of the necessary info in this thread? I have a set of 1997's that I am going to rebuild and would like to emulate what you have done.

If you have any other research you would like to share offline: sharsila@hotmail.com
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Post by bradf »

Most everything is here but I do have a word doc with the shim stacks and all other info. Remember that my fork info is for 99-02's and possibly later. I don't know if 97's with CV can be made to have a MV stack.
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Post by KDXer »

I'd love a copy for comparison sake if possible. My email link is on the toolbar thingy below. Cheers, Trev... :prayer:
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Post by m0rie »

95+ KX 125/250 forks had a MV so i'd imagine that while perhaps not using identical stacks to the 99-02 forks they would benefit from a good starting point.
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Post by Indawoods »

And they still click. :wink:
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