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CR85/CR125 fork valving

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Seeing that a fork swap is no longer satisfactory and we now have  to perfect the valving of those forks for our woods machine "150/230 I figured that we could use this thread to post our information on shim stacks and and modifications that works best.

What are we trying to achieve?

Are we trying to reduce high speed damping?

Are we trying to reduce low speed damping?

I have been following a thread from BTR where he modified his mid-valve, what are your thought?

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Primarily we are trying to reduce high speed damping and also make sure low speed damping is kinda loose so to speak.  Fork spring preload and float have an effect on low speed damping being too stiff.

I'd have to read up on BTR's mod more to understand the why and how.

There is lots of revalving info over in the Suspension section but it's not easy to track down "plushness for woods" type solutions.  I have been learnding allot while perusing that section and starting threads.  I have even gotten a copy of the "Suspension Bible". 

What fork will you be using?  Do you know what the current shim stacks look like, what is the shim list?  It's customary to list the shims starting from the piston with what is called the face shim.  Sometimes just a reshuffle of what you have now will work.  Sometimes you need to procure more shims of varying diameters and thicknesses.  This might be easier for you where you are by purchasing some used forks that are damaged or some used fork parts.  Even for us living in the USA, the price for one shim gets inflated by buying in bulk packs and then paying shipping. 

Another option is to buy a RaceTech Gold Valve for the forks which will come with all shims necessary as well as instructions on how to revalve for your desired effect. 

Edited by MetricMuscle

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Lets try to focus on the CR85 Showa forks and the CR125 KYB forks.

I don't want to get in to the Gold Valve system as they already have their recommendations.

From what I've been reading most ppl remove a few of the low speed shims to get a plusher ride and keep the same shape of the stack but then we have the problem of harshness from the mid valve.

Looking at the stacks on these forks it seems that they have a 2 stage stack, why not create a 3 stage stack with possibly the same amount of shims?

wouldn't that give us the opportunity to make the low speed plusher and a more transitional high speed for when the mid valve kicks in? 

 

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The way I understand things is that the Base Valve handles most of the compression damping whilst the Mid Valve the rebound.  Most MX forks don't have to deal with high speed suspension hits so the high speed valving is typically too firm.  The tapered part of the stack is the High Speed part.  The Face Shims are the low speed.

Since both of these forks are Open Chamber, you don't have to worry about the ICS spring and it's effect on compression damping.

Might you know what you have now for a shim stack?

Have you ridden with either fork installed yet?

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2 minutes ago, MetricMuscle said:

The way I understand things is that the Base Valve handles most of the compression damping whilst the Mid Valve the rebound.  Most MX forks don't have to deal with high speed suspension hits so the high speed valving is typically too firm.  The tapered part of the stack is the High Speed part.  The Face Shims are the low speed.

Since both of these forks are Open Chamber, you don't have to worry about the ICS spring and it's effect on compression damping.

Might you know what you have now for a shim stack?

Have you ridden with either fork installed yet?

Still in the process of doing the CR125 install so no I haven't ridden with them yet, but I'm certain I'll be pulling them back down in the near future looking for improvement.

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8 minutes ago, ROD Kerry said:

Still in the process of doing the CR125 install so no I haven't ridden with them yet, but I'm certain I'll be pulling them back down in the near future looking for improvement.

Any idea the history of the forks?  Have they been revalved from OE?

The Showa 47mm TC forks I am working on have been revalved and some of the OE shim sizes are missing.

Knowing what the Face Shims and the HS stack looks like can give you a better starting point.  Do the forks need to be serviced and have the oil changed?  You don't need to take them completely apart to look at the BV and MV.

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8 hours ago, MetricMuscle said:

Primarily we are trying to reduce high speed damping and also make sure low speed damping is kinda loose so to speak.  Fork spring preload and float have an effect on low speed damping being too stiff.

I'd have to read up on BTR's mod more to understand the why and how.

There is lots of revalving info over in the Suspension section but it's not easy to track down "plushness for woods" type solutions.  I have been learnding allot while perusing that section and starting threads.  I have even gotten a copy of the "Suspension Bible". 

What fork will you be using?  Do you know what the current shim stacks look like, what is the shim list?  It's customary to list the shims starting from the piston with what is called the face shim.  Sometimes just a reshuffle of what you have now will work.  Sometimes you need to procure more shims of varying diameters and thicknesses.  This might be easier for you where you are by purchasing some used forks that are damaged or some used fork parts.  Even for us living in the USA, the price for one shim gets inflated by buying in bulk packs and then paying shipping. 

Another option is to buy a RaceTech Gold Valve for the forks which will come with all shims necessary as well as instructions on how to revalve for your desired effect. 

I need disagree on Gold valve comes with all shims necessary. Im sorry to all I repeat Racetec has no clue on trail susp. Here is the skinny they sell you the gold valve(we just bought two sets) It says this kit has the shims you need.   In the packet of shims they give you Most of them all the same size. That you do not need,then your forced to buy the shims you need.Like we did,also nowhere when you buy the gold valve. Does racetec tell you there gold valve,cannot work without Mid valve mod. Nothing new as we have been playing with gold valves for years. Unless you know someone. That has there gold valve working in same bike you have.Same type riding you will be taking it apart over and over. Just like we are doing. Im ok with the hundred hours,taking the forks apart,Other then riding I have time. The Forks loaned to me that have shim stack, is not on any ractec sheet. I cant complain worked great on our 76 mile run. Here is the problem we did my forks other day,we left out 1 more shim. Big mistake it now jolts me high speed square edge. To verify this tomorrow 105 mile ride,two other testers. If so take apart 5th time do shim shack just like loaner fork Done. On this fork when you turn in rebound more hard,it makes comp hard at same time. One thing positive 100%    Do mid stack valve mod day and night better.

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If/when I get aftermarket cartridge valves I'll get both Base and Mid.  Thanks for the info, I didn't realize they didn't come with a nice assortment of shims.  Maybe they expect you to use some of the OE shims.

Soon I too will be experimenting with some CR85R/150R forks.  :)

 

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11 minutes ago, MetricMuscle said:

If/when I get aftermarket cartridge valves I'll get both Base and Mid.  Thanks for the info, I didn't realize they didn't come with a nice assortment of shims.  Maybe they expect you to use some of the OE shims.

Soon I too will be experimenting with some CR85R/150R forks.  :)

 

Ok MM I dont think you can use OEM shim in gold valve. As far as CR85 fork there all the same size. There shim kit I think came with 10 number 17 shims. What the hell is that about,we buy the gold valve. Then the shims you need not there?  I will say great Idea from recetec making gold valve. Since its been out over 10 years you would think they would have the right shims in the box. Lucky for you guys When Im done just copy me do it first time.

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Great news other day the place where my bike jolted me over. Three test rain ruts my mentor on same test said I was going 70mph. According to his bike, also said his bike jolted him too. Also said you dummy nothing can go over that fast, lucky we did not crash. So we turned around we hit it in 5th gear 50mph smooth as glass. I rode bike on beach over we call Moon rocks. Both testers also said your done dont touch it anymore. So I already give you washer spacer size for mid valve.1st Valve code Gold valve  Starting at top    .10X9   .10X17 (2)   .10X11   .10X15      .10X13    .10X11  .10X10      .10X11   Rebound from hard turned out 2 1/2 turns    Comp full soft    5wt oil 4in from top.   Second valve code Mine current the  .10X 13 shim removed. The first Valve code I would recommend for faster trail riders over 175 pounds. For under 175 pounds slower trails and slight more plush Second valve code. This is for trail riding not racing woops,for that leave it stock. You cant have both since these bikes590a5987deb88_IMG_20170503_113135814moonrocks.jpg.ccb8c14361c55557a704f7b342e08275.jpg never will do woops like a 450. Who cares. Next test Gold valve V moded stock base valve.  Million thanks to Chuck,Mike and Dave the susp Man. 

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I have the 150R forks on my 230 and I desperately need some help to tune them. Step one was to add the .40 race tech springs and get the static sag set ok. I disassembled and cleaned and refilled with 5wt synthetic fork oil. I played with oil levels and now have it set with acceptable bottoming resistance, about 4.5" from the top. They seem very harsh and not real compliant for enduro/trail riding over roots and ruts. I ended up with the clickers all the way out.

Will any of the 85R mods work on the 150R forks? Otherwise, what have others done to 150R forks to get a nice compliant ride in the woods?

Initially the springs were too soft and the bike had way too much sag and uncontrolled brake dive. That has been corrected with the .40 springs. I really like the way the bike sits and I can really push it hard now, but the harshness gets to me tired pretty quickly. Any help is appreciated

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Chuck Knows those forks PM Chuck. If it has same mid valve (as CR85) do the mod I posted. My bike is also for trail and I demand plush ride. Since I dont know CR150r Base valve. If you put Gold valve in to my spec you will like it. If your from 150 pounds to 200 pounds. Thats what me and testers are. Day and night more plush then stock.

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Forgot to add. Talking to the two other riders last night,that helped me dial in forks. I had one watching my forks,the other riding on other side. Watching back end. On front forks they said Its right. As front forks moving up and down taking all bumps,and handle bars steady as a rock. Rider watching back end Fox shocked. Said forks now more plush the rear end. We now have a Fox shock with custom 1 off Valve code for Mikes bike. Problem long time to test,till Terry gets our 250cc piston shipped to Mike.

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16 hours ago, bajatrailrider said:

Great news other day the place where my bike jolted me over. Three test rain ruts my mentor on same test said I was going 70mph. According to his bike, also said his bike jolted him too. Also said you dummy nothing can go over that fast, lucky we did not crash. So we turned around we hit it in 5th gear 50mph smooth as glass. I rode bike on beach over we call Moon rocks. Both testers also said your done dont touch it anymore. So I already give you washer spacer size for mid valve.1st Valve code Gold valve   Starting at top    .10X9   .10X17 (2)   .10X11   .10X15      .10X13    .10X11  .10X10      .10X11   Rebound from hard turned out 2 1/2 turns    Comp full soft    5wt oil 4in from top.   Second valve code Mine current the  .10X 13 shim removed. The first Valve code I would recommend for faster trail riders over 175 pounds. For under 175 pounds slower trails and slight more plush Second valve code. This is for trail riding not racing woops,for that leave it stock. You cant have both since these bikes590a5987deb88_IMG_20170503_113135814moonrocks.jpg.ccb8c14361c55557a704f7b342e08275.jpg never will do woops like a 450. Who cares. Next test Gold valve V moded stock base valve.  Million thanks to Chuck,Mike and Dave the susp Man. 

Looking at your shims I realize that your face shim isn't the largest of them, wasn't the face shim on the stock valve the largest.

This is information you usually have to pay for. Damnnn. I only wish I had this for the Cr125 forks.

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Dont understand but. This report my first Valve code (Not listed by me) was somewhere in Racetecs Spec. Was zero improvement over stock moded base valve. As I stated new listed valve codes not on any racetec chart or recommendation from them. Also none of the mods where my doing.Im only the tester with Thanks a Million to Dave his test Mid valve mod and baseline valve code made it right. He has no knowledge of Cr85 fork on 230s. No less he was right on with the mods,with me having unlimited time. To test and report to him and changes. It would be real nice if one other Cr forked  230 rider did same mod as me and reported. So far only Me and Mike have the moded forks,and my Non gold valve Cr forked other 230. Chuck is very Sharp on Cr85/150 forks I wish he would do mod and report back on findings.

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29 minutes ago, ROD Kerry said:

Looking at your shims I realize that your face shim isn't the largest of them, wasn't the face shim on the stock valve the largest.

This is information you usually have to pay for. Damnnn. I only wish I had this for the Cr125 forks.

If I understand you. Your talking about Stock base valve V gold valve Shim ?  If so stock base valve has all 11 shims same size.

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The small first shim adds some float to the stack and makes the valve leaky, which improves plushness and makes the clickers usable for ride tuning. I'm going to try it.

96+ CR80/85 forks are the same as CRF150R forks except for the size of the axle hole and valving/spring.  However Honda did a lot of shim stack and valve body changes over the years, and tuners change valving, so  you really don't know what is inside used forks. Here is a list of Honda part numbers for the valving:

Base valve #51441-

  •      GBF-831         96-97 CR80R
  •      GBF-831         96-98 CR80RB
  •      GBF-J01         98 CR80R
  •      GBF-J21         99-02 CR80R/RB
  •      GBF-K01        03 CR85R/RB
  •      GBF-K21        04-07 CR85R/RB
  •      KSE-671         07-08 CRF150R/RB

Rod, Damper #51480-

  •     GBF-831         96-97 CR80R
  •     GBF-861         96-98 CR80RB
  •    GBF-J01         98 CR80R
  •     GBF-J21         99-02 CR80R
  •     GBF-J31         99-02 CR80RB
  •     GBF-K01        03 CR85R
  •     GBF-K11        03 CR85RB
  •     GBF-K21        04 CR85R
  •     GBF-K31        04-07 CR85RB
  •     KSE-671         07-08 CRF150R
  •     KSE-841         07-08 CRF150RB

A lot of the other part numbers also changed over the years but the above are pertinent to this discussion.

 

 

Edited by Chuck.
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Ok guys Back to Back test done today Gold valve V modded base valve. Me and nit picker Tested. For you budget mined guys. The stock base valve with all mods done to it work so good. Are as good as gold valve,even nit picker could not complain. My opinion maybe gold valve very slight bit better. You would not know it unless you had two bikes to compare,its that close.IMG_20170329_181331318_HDR.jpg.c00ed937daa5e5266712511fc5862271.jpg  On that bike Mid valve mod done, 6 of 11 shims removed all three holes in stock base valve drilled bigger also one extra hole drilled on side of base valve. .40 spring, comp on full soft,rebound 1 turn out from hard. Oil 4in from top  3wt rear shock oil.

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I have the 150R forks on my 230 and I desperately need some help to tune them. Step one was to add the .40 race tech springs and get the static sag set ok. I disassembled and cleaned and refilled with 5wt synthetic fork oil. I played with oil levels and now have it set with acceptable bottoming resistance, about 4.5" from the top. They seem very harsh and not real compliant for enduro/trail riding over roots and ruts. I ended up with the clickers all the way out.  

Will any of the 85R mods work on the 150R forks? Otherwise, what have others done to 150R forks to get a nice compliant ride in the woods?

 

Initially the springs were too soft and the bike had way too much sag and uncontrolled brake dive. That has been corrected with the .40 springs. I really like the way the bike sits and I can really push it hard now, but the harshness gets to me tired pretty quickly. Any help is appreciated

 

I have no knowledge of 150R forks, but assume by looking at them they are a dual/closed chamber inverted design similar in function to the 47mm Showas found on most Honda CRFs. If so, I'm not sure how you are setting oil volume. These forks should have a measured amount added to the outer chamber within the max/min amounts listed in your owners manual. It's important to get this correct, and you may wish to start on the low side to soften things up. The inner chamber oul volume is a fixed amount you set by properly bleeding them. Hopefully, you're not lowering the oil level in this cartridge, since that would create a number of problems.

 

You can soften your forks for off-road by altering your Midvalve (MV) and Basevalve (BV) shim stacks and MV float. This is not difficult to do if you have good technical information, like Race Tech's Motorcycle Suspension Bible.

 

The MV plays a significant role in fork harshness. Oil passes through it about eight times as fast as the BV. Therefore, it experiences hydraulic drag (similar to aerodynamic drag) and it's resultant hydraulic flow restriction (harshness) much earlier than the BV. As velocity doubles, drag quadruples. Eight times the velocity results in drag increasing 64 times, so you can see how important the MV valving is to damping/harshness control. Both the BV and MV compression valving work together to create compression damping. Only the MV rebound stack controls rebound.

 

Your BV may also include a Bleed Stack. If so, you will probably want to open it's flow up by "flipping" this stack upside down to allow more free bleed on the compression stroke.

 

For offroad, MX forks like yours can be improved by softening both the BV and MV shim stacks. Your BV is most likely a two stage stack. It's Low Speed (LS) stack can be softened by removing some face shims. It's important not to remove too many, or to use too small of a crossover shim since this can actually make the forks harsher. This is because making a LS stack too soft allows it to "cross over" into the HS stack too soon. This engages all the shims in both the LS and HS stacks, which creates greater hydraulic resistance/damping/harshness. For "woods" riding, most riders prefer softer BV LS and HS stacks, as well as a softened MV comp stack with more float than an MX setup.

 

All this is relatively simple to accomplish once you have your forks apart and measure all your shims and MV comp float dowel. Keep everything organized and do one fork at a time just in case things get out of place.

 

From this information you can "shuffle" shims around to make calculated guesses at altering your damping.

 

Basically. From a stock MX setup, you'll want to remove a few BV face shims (LS), as well as a number of HS shims. It's common to remove all the odd shims in the HS stack. The removed shims are "shuffled" after the clamp shim from smallest to largest to maintain total stack height while rendering them non-flexing.

 

For the MV comp, which is typically a single stage stack, most remove some face shims and increase float a bit.

 

This may seem unclear, but once armed with a good manual (Suspension Bible) and some hands on experience while carefully tearing the forks apart things will make more sense.

 

There are many TT members available to make specific recommendations once you post your stacks.

 

Or. You can send them to a tuner and hope for the best after spending around $600 front and rear.

 

Good luck!

 

 

 

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I have no knowledge of 150R forks, but assume by looking at them they are a dual/closed chamber inverted design similar in function to the 47mm Showas found on most Honda CRFs.

They're NOT dual chamber. A quick look at the parts catalog or service manual tells the tale. :naughty:

Also, see other posts by bajatrailrider and others for recommended valving changes.

:ride:

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