YZF Suspension Midvalve??

80 replies to this topic
  • DaveJ

Posted November 13, 2001 - 03:27 PM


In my opinion, I would leave the new seals along. Keep doing like you do and clean them, and make sure that you don't get dirt or water spot build up on the fork tubes.

As for oil, I think both forks take about 1.5 quarts.

  • Scott_F

Posted November 14, 2001 - 06:39 AM


I agree, leave the seal springs alone, and two quarts will probably not be enough for both front and rear.

  • forloop

Posted November 14, 2001 - 08:54 AM


I always trim mine. I greese and clean mine often too. I have never noticed any more stickion than not trimming them. In my case they sure last longer. They will break in no matter what you do.

My seals on my bike started leaking right after I got it. I changed the seals with trimmed ones and no problems since.

If it was me, I would.

How's the collor bone doing?

  • motoman393

Posted November 18, 2001 - 01:14 PM


I just thought I would give you guys an update on my suspension. Because my bike looks like it has seriously "blown up" in the garage, from all the parts (front and rear suspension, swingarm, wheels, subframe, muffler, etc) Now it doesnt even resemble a bike LOL! I am glad I painted the garage floor now, because their is US-1 oil everywhere!

Yesterday I installed the Gold Valve and new rear spring in my shock and reassembled everything. It was much easier than I expected (alot easier than forks IMO). The hardest part was removing the circlips and figuring out which shim was which (the Race Tech video is really helpful)! I am going to a local suspension shop tomorrow to get it charged with Nitrogen.

I started on the forks today and I am almost done. I just finished removing the seal head. And boy was this a pain (literally)! I tried to remove the seal head by just gripping it with a leather glove and squeezing the hell out of it...it didnt work, and successfully gave me nice blisters :) I finally came up with the ingenious idea of using PVC pipe to unscrew the seal head. I got about a 3ft piece of PVC pipe that fit over the "+" shaped top and then I cut 4 grooves in it with a Dremel. I then drilled a hole (all the way through) midway up the pipe, and stuck a screwdriver in it (to give me leverage) This made it easy! Thanks for the tips on not drilling too far...you dont have to drill far at all!

Well I cant wait to test it out at the track! I am really glad I did this job myself...because in the process I have learned so much! The hardest part was convincing myself to take apart $1000+ suspension and risk screwing it up! I now realize how the shim's thickness and diameter affect the compression and rebound (it is actually really cool) I just thought I would let the guys who have taken their suspension completely apart know. Because everyone I try to tell what I am doing cant follow, because they havent seen the internals! Well thanks for all your help you guys are great. I will let you know when it is "completely" finished! Thanks,


[ November 18, 2001: Message edited by: motoman393 ]

  • BK14MX

Posted November 18, 2001 - 05:27 PM


hey motoman, theres was a pretty cool suggestion in one of the recent magazine issues about fork seal care. Tom Moen(believe that was his name), he's a Factory KTM guroo, basically just pull down the dust wipers, clean thoroughly with contact cleaner, then spray some type of lube, he suggested something heavier than WD-40,(I used silicone spray), inside the dust wiper. Then just slide it back up. Its works great on ending stiction, actually much better than I thougth it would. I just do that after every wash/ride, helps greatly on small chop.!!

[ November 18, 2001: Message edited by: BK14MX ]

  • motoman393

Posted November 18, 2001 - 06:00 PM



I also read that in Dec. 01' Dirt Rider. I use a similar lubricant every time I ride my bike, it is a dry teflon lube, and it works very well. This is why my stock seals have lasted exactly 1yr and they still are good/non-leaking (but I am replacing them anyway since they are old) Later,


  • MX_Tuner

Posted November 19, 2001 - 07:36 AM


What valve stack did you use in the forks?

  • DaveJ

Posted November 19, 2001 - 08:35 AM


MX Tuner,

Who is your question directed to?


  • motoman393

Posted November 19, 2001 - 09:29 AM


MX Tuner,

I havent changed the shims/installed the gold valve in my forks yet (they are still apart in my garage) I had to completely finish the shock and linkage (so I dont get parts confused/misplaced)! I am revalving them either tonight on tomorrow morning. I was going to use Race Tech's recommended setup (and change it if I dont like it) Here is what they call for:

Low Speed Compression Valving = cL6
High Speed Compression Valving= cH5
Oil Level= 90mm
Compression Adjuster= 10 out
Rebound Adjuster= 14 out
Fork spring preload= 8mm
Fork Spring set length= 453mm
My springs are .44's
and remember I weigh 168lbs w/o gear

(2) .15 x 21
.10 x 13

(2).10 x 21
.10 x 19
.10 x 17
.10 x 14
.10 x 13
.10 x 12
.10 x 11

You mentioned that Race Tech's valve setup will be too harsh? If you have a stack recommendation I would love to hear from you! Thanks a bunch,


  • MX_Tuner

Posted November 20, 2001 - 02:12 AM


Dave, I was asking Motoman what RT's recommended stack was.

Going with their stack will give a stiff ride (with a capital S). I've e-mailed you what I'd try.

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • motoman393

Posted November 20, 2001 - 08:54 AM


Suspension gurus,

I am almost through with my forks and I am stuck in a bind! How are you guys removing the Valve holder from the damping rod (#'s 19 and 21 in the race tech instructions, inside the cartridge) it says that if I dont install the cylinder seal then make the compression valving stiffer. But, I want to install the cylinder seal, because I dont want to take any shortcuts! I would really appreciate any help that you can give because I would like to get these forks done today! Thanks,


  • DaveJ

Posted November 20, 2001 - 03:38 PM



I'm not sure what you're talking about, but I can make some assumptions.

It sounds like you have already drilled the peens that are pressed into the top of the cartridge, and have removed the valve head (aka, seal head, or cylinder valve head).

When this comes out, you can slide out the rod, removing it from the cylinder. To install that Race Tech valve seal, you have to remove the piston and valve assembly from the end of the rod, (this assembly, is also the assembly that contains the mid-valve, in which you'll install the Race-Tech check-plate).

To remove this, you'll need a 15mm wrench, to fit over the cut width, just above the rebound spring (that short heavy spring that makes contact with the seal head when you extend the forks).

Since this assembly is loctited, you may have to heat it, but stay away from the rod since the heat can damage the rod coating. It's a toug process.

To hold the rod, you'll want two nuts to thread on the end of the rod. Lock them down on each other, then use a socket or wrench to hold them in place. Protect the rod with plenty of towels in case of slippage. By the way, those lock nuts are a common metric size and thread, so most hardware stores stock them.

Be careful not to damage the threads by allowing the nuts to shift or move during this process.

When the rebound piston assembly comes off, there will be a small spring that loves to escape into small corners of the garage. Keep your eyes and hands ready and don't forget to put it back in place on the re-assembly.

There's also a needle in the rod, but it's sealed so it seldom falls out.

Let me know if I'm way off from what you're looking for.

I'm sure ScottF and others may have some great tips as well.


  • Paul_Thistle

Posted November 20, 2001 - 05:24 PM


Motoman, I use a dampning rod holding tool, and I clamp with this tool where the spring spacer is at the top so if i goob up it don't matter. Then I heat the steel rebound valve holder to 300 F. It will then unscrew easily. As Dave said only heat the steel end. PT

  • motoman393

Posted November 20, 2001 - 07:17 PM


DaveJ and others,

The main reason that I need to remove the valve holder from the damping rod (these are the names race tech uses) because I need to install the cylinder seal that race tech gave me and I have to remove the valve holder first (this piece is at the very end of the damping rod and is the piece the mid valve, spring, and shims go on, it is Stainless steel like you said)) If I dont install the cylinder seal, (it will still work) But they say the cylinder seal, "makes the valving much more consistent, firmer and plusher as well" ...But if I dont install it I need to go up 3 on the low speed compression stack and 1 on the high speed compression stack due to "blowby" (which would mean a recommended stack of cL9 cH6). This is what Brad @ race tech told me. Have any of you guys installed gold valves w/o using the cylinder seal? Did you really have to go stiffer on the valving like race tech recommends?

So you are saying if I get 2 nuts and thread them on the end of the damping rod (and snug them up) I will be able to get the valve holder off to install the cylinder seal? Because that piece seems like it is in there pretty good! A socket wont fit the end piece either it is shpaed like this (it doesnt have 6 sides like normal, only 2 straight sides and 2 curved ends):

and a regular socket wont fit, only a crescent wrench would work or an 18mm (I think)

I already removed the midvalve and installed the check plate (this was real easy to do) and all I have to do is decide which stack I am going to use, and install the cylinder seal (only if I can get that piece off) and then reassemble everything! Thanks for your help...all my frustration Im sure will be worth it whenever I have a bike that rides like a "Cadillac" on the dirt because it as already as fast as a dragster LOL! Thanks,

Garrett Berg

  • motoman393

Posted November 20, 2001 - 07:23 PM


Also I was thinking of polishing the damping rods while I have them apart (because I can tell they need it). I would just use 600 grit wet sandpaper right? Im sure this gives good results, less friction?

  • DaveJ

Posted November 20, 2001 - 09:36 PM



First of all, DO NOT polish the compression rods. They are coated with a special soft material that is designed to work with the valve head bushing.

They are not meant to be shiny and smooth like you might expect. If they have any groves where you can see shiny material, they need to be replaced or smoothed and re-coated.

Good thing you said something because it's a costly process to fix this. Ignore any instructions that Race Tech provides recommending that you do this.

As for that valve assembly that you're trying to remove, you're right. It's really on there. You cannot hold the rod with anything other than a set of lock nuts. And I thought the only tool that fit this was an open-end 15mm. I could be wrong about the size.

I would recommend removing the valve shims and piston, then applying some concentrated heat to the area, but don't smoke the rod coating.

Place the assembly on the table, with plenty of towels and apply pressure evenly to avoid a tool slippage.

Now, should you install this plate that Race Tech is talking about?

If you remove the mid-valve I would install it. If you don't remove the mid-valve, I would leave it along. What I don't like about this plate is that works as a patch, running interference with the function of the seal head. It's a great combo if you run bottoming cones, but things seem to get goofy in the long run when this plate is used with the factory seal head.

Also, Race Tech made the plate too thick. Which means you'll most likely find that the seal head does not screw down as far as it did without the plate in there. Perhaps they fixed this compared to when I was last working with their stuff.

And I'm sure you have seen my earlier post about the drilled peen holes leaking post assembly.

Hope this helps.


  • Scott_F

Posted November 21, 2001 - 06:15 AM


There is another way to get the shaft out of the cartridge. You can remove the tiny bottom out piston and the rod will slide out the bottom of the cartridge. This method is used when installing bottoming cones, since the piston is being replaced anyway.

To hold the damper rod, you can try double nutting it, or buy a damper rod holder. Like Paul said, if you clamp it up high where the spring spacer is, you won't risk damaging it where it slides through the bushing. This delicate rod is aluminum, anodized and teflon coated. As DaveJ knows all too well, you do not want to anything to harm the finish of this expensive part.

  • motoman393

Posted November 21, 2001 - 07:14 AM



Yesterday, I thought of that same idea of using the lock nut to remove the end piece, but I thought it would damage the threads (if you only knew some of the things I tried to get it off LOL)! Well I just now removed the 2 pieces off both the damping rods and it was very easy to do with the 2 lock nuts method. I really appreciate it...well I better get back to putting my forks together I will let you know how it goes when I get finished! Thanks,


  • motoman393

Posted November 21, 2001 - 07:29 PM


Well I got my suspension COMPLETELEY done...whew! Man was it frustrating and time consuming! But I think it was well worth it and I havent even ridden the bike yet! I have learned so much and now I could easily do it in half the time! It feels rather stiff right now (I havent ridden it yet, just sat on it) I am thinking the springs just need to be broken in. Tomorrow I will set my sag and get it "prepped" to be ridden in 10 days...the doctor said wait 10 more days (arghhh LOL)

MX Tuner,

I went ahead and used RT's recommended valve stack, just so I could be at a "base". Whenever I ride it and after I break in the springs I will see how it is. If it is too harsh or stiff I will be swapping out shims to your specs! Thanks a bunch, I owe ya one! Later,


Whenever I go back to the track in Splendora in about 2 wks...I will take some pics of the triple I wrecked on, and post it up here!

[ November 21, 2001: Message edited by: motoman393 ]

  • thumpy

Posted November 22, 2001 - 04:56 AM


Hey motoman,

I missed the explanation of how you wrecked. What happened and what did you injur?

Related Content


100 hrs on 2014 yz450f, shim valves or replace them? by ttr230rider6

Dirt Bike   Make / Model Specific   Yamaha   YZ 400/426/450
  • Hot  79 replies

yz400f throttle bog by yz400fmaniac

Dirt Bike   Make / Model Specific   Yamaha   YZ 400/426/450
  • * * * * *
  • Hot  28 replies

Chubby dad, looking at bikes , First trip to the orange/black forum ! by Slow_ride

Dirt Bike   Make / Model Specific   KTM   250-530 EXC/MXC/SXC/XC-W/XCR-W (4-Strokes)
  • Hot  28 replies

2016 YZ450 by CaptainKnobby

Dirt Bike   Dirt Bike Technical Forums   Suspension
  • Hot  59 replies
WR Camshaft Swap Info - last post by jamesm113

WR Camshaft Swap Info

  • 0 replies

Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.