06' CRF250R woods shim stack

[See-Are-Ef-Too-Thir-T-Ef]

Hey, I'm racing AMRA hare scrambles and qualifiers in Arizona, which are generally tight, extremely rocky and have tons of square edges. I really need a suggestion on a woods shim stack, i've put up with the stock R stuff for a year now and can't deal any longer.

It seems like a common thing to do is to take out 5 or 6 16mm shims and then add 5 or 6 30mm shims with the 30mm stack. Also, will I need to drill out the base valve? I've never done this before, but I have replaced seals and whatnot, and im willing to learn! Thanks

[MRW]

Check out the crf450 forum, up in the pinned section look for the re valve article

posted by "The Dogger":ride: All kind of stacks in there:ride:

[Zac]

reduce the preload on your spring machining a new cave in the rod

You can manchine 2 cave, 1cm and 1.5cm.

In enduro and HS you have to have 3.5 cm of sag, in motocross you have less.

Stock shim stack.Less oil in the tube.

You will have a plusher fork in the first 5cm of travel to gain sensibility in slippery rocky condition

If you are less than 70kg, you can use softer springs.

For your shock, let the racesag at 12cm instead of 9.5.

Stock shim stack

Zac (our rider is totally satisfied of those cheap modify and gain a 3rd in district championship...)

[MRW]

You can also turn down (shorten) the spring seats to reduce preload on the fork springs 3 to 5mm. For some people this way may be easier depending on their lathe setup.

[See-Are-Ef-Too-Thir-T-Ef]

Actually I think I'm getting into changing the shim stacks and different springs of course. I have a feeling there is so much good help on here I can't go too wrong.

[plasticseatsweat]

I was helping a friend revalve his 05 kx250 today and we tore the forks down to see what the stock shim stacks are. I have been told that in general when valving an MX bike for off road you can remove about half of the low speed shims(largest diameter) from the compression stacks. This is what I have done with my KTM and have drastically improved the suspension action in the rocky stuff. Today was my first time revalving twin chamber forks, but it's all the same principle. Most bikes seem to have multiple's of the largest diameter shims stacked on top of each other, the kx had 5-22's stacked ontop of each other. This may work on a groomed mx track but not off road, small trail junk isn't going to flex that stock stack. I you can't find any info specific to your bike I would experiment like I have and I think you'll find the same the same thing, and it's cheap and easy.

[EddieTNT]

Ooops!

[EddieTNT]

Add a crossover shim in the appropriate place then remove at least half of the largest diameter low speed shims. Also remove about 1/3 of the high speed shims and use this new setting for your first trial. Lighten up the midvalve as well. I don't reommend removing the midvalve entirely in the TC forks. You will become intimately familiar with your shim stacks before you get it the way you want it. Keep plugging. It will take several (many) attempts to get it dialed in. Trial and error is the rule of the day.

[frezno]

Lighten up the midvalve as well.

I'd stay with the mid (or only soften it very lightly) to keep the fork up in the stroke.

And if you touch the mid, first try changing the base as suggested and try this new setting.

With too many changes you don't know which change causes what behaviour.

[EddieTNT]

My recommendation was only to establish a baseline from which to begin working. I agree don't soften the mid-valve too radically.

[sandfly]

I did my 06 and it's great. I don't know if i have tme here to give you all my info but man it was well worth it.

I am 215# with all my gear

I run .48's in the front

I lowered my oil height to the min 305ml as you can add it later if you find them to soft. To take oil out though you have to take the forks appart and do everything all over again wich is very time consuming.

The stock shim stack was something like this. I have indicated the ones i removed.

(16) 30X.10's (Remove 4)

(1) 29X.10 (Remove)

(1) 28X.10

(1) 27X.10 (Remove)

(1) 26X.10

(1) 25X.10 (Remove)

(1) 24X.10

(1) 23X.10 (Remove)

(1) 22X.10

(1) 21X.10 (Remove)

(1) 20X.10

(1) 19X.10 (Remove)

(1) 18X.10

The ones i remove i flipped upside down and icluded them in the stack but because they are flipped they are not part of the circuit. For this procedure and to get at the shimstack, take a look at the first few pages of the revalve sticky at the top of the CRF forum.

I also remove (2) 16X.10's from the mid valve which makes the float .30

The tighter the float the more responsive the forks will become as there is less bleed

Off roaders need more float. More bleed to the base valve. This allows more oil to flow past the mid (by removing shims) and will make the fork move though the stroke quicker.

These are all very general statements i am making as this is a very difficult subject to truly understand. What i can say is though that my forks are a whole shitload better now that i have made these changes. As well, the bike can still be used for mild MX. I have no regrets thanks to the CRF sticky and many of hours of reading. I am still learning as well.

In fact this setup works so well for me off road i will probly leave it as is. As well, if you do not want to revalve, you can of course start with the righ springs and then play around with oil levels as this has a huge effect on plushness.

I would love for someone to try this stack and let me know what they think.

[sandfly]

Hey, I'm racing AMRA hare scrambles and qualifiers in Arizona, which are generally tight, extremely rocky and have tons of square edges. I really need a suggestion on a woods shim stack, i've put up with the stock R stuff for a year now and can't deal any longer.

It seems like a common thing to do is to take out 5 or 6 16mm shims and then add 5 or 6 30mm shims with the 30mm stack. Also, will I need to drill out the base valve? I've never done this before, but I have replaced seals and whatnot, and im willing to learn! Thanks

Do not drill anything!

To get at the base valve shims you have to remove the peening at the end of the threads on the base valve. It's not a big deal just be careful as you are dealing with aluminum. After you do this you can spin the nut off to get access to the shims. Lay everything in order as you take it off so you can put everything back together corectly.

[KTM-Lew]

The largest of the shims, and usually found in multiples, are your high speed shims.

Wrong...the largest shims, the ones touching the piston, are considered low speed shims.

[sandfly]

Wrong...the largest shims, the ones touching the piston, are considered low speed shims.

Yup. I stand corrected. I was just looking at the sticky to verify that. You diden't give me enough time to correct my error. I think you were waiting in the shadows to jump on me weren't you

[See-Are-Ef-Too-Thir-T-Ef]

Ok, I finally got her apart! Took me awhile but here I am, me and my base valve. I am choosing just to touch the base valve right now out of simplicity. It looks like if you want to get the peening off, you have to grind right up to the nut. Does this leave enough threads for the nut?

Here is a crude picture, sorry my freehand paint is like a 4 year old.

I am guessing on what some of these parts are:

A baseplate, B shim stack, C valve, D random shaft?, E slider bushing seal?, F sits infront of the valve, G saucer shaped fat washer between F and end nut, H inner chamber spring(pressure spring?).

Okay, so I plan on removing 4 of the biggest and put them on the end next to the baseplate? Also, people removed all of the odds on the way down (29-19mm) and put them also next to the baseplate? I am 160 pounds, slow to mid B level harescramble/enduro, lots of loose rocks and chop. Rocks and square edges cause too much defelction and harshness. .42 and 5.0 springs. What do you guys think? Thank you.

[See-Are-Ef-Too-Thir-T-Ef]

Anyone...?

[MRW]

Sounds good. Looks like you did your home work:ride:

I would also use 360cc in the outer chamber verses the standard(for most)of 350cc for woods due to the fact that you are running lighter than stock springs which are thinner diameter wire which requires slightly more fluid to equal the same "air spring effect". The Honda manuals make note of this in the suspension section of the manual.

I think they estimate 5cc per spring rate change.

Also, running a count of (5) 16mm face shims in the base control valve is another good idea for woods. This is the small stack located just under the "A"(base plate) in your pictures. Just flip them on top of the stack right against the base plate. Same thing you are doing with the "odds" and the "30`s" on the Base Valve side of the base plate.

You will love your forks now:ride: ? Good job, you just built a Showa/KYB fork! Well kinda,IMO.

Note...removing those "odd" shims from the Base Valve feels just about the same as pulling (1) 20mm from the Mid Valve.But easier.

As far as grinding the nut. Just grind it straight flat until both surfaces are smooth(the shaft and the nut). Then try taking the nut off. If it is still tight , grind a little more. There are plenty of threads on the Showa`s. Sometimes you may have to "dress" the threads with a small file after everything is removed(base valve, shims, etc) so the nut goes back on nice and easy.

Make sure all is clean before assembly. Don`t want any metal shaving in there!

[See-Are-Ef-Too-Thir-T-Ef]

Thanks, this is cool stuff.

So, I will take those (5) 16mm shims(they are left of the base plate as in the picture) and put them sandwiched between the baseplate and the (4) 30mm's, on the right hand side of the base plate. Also I will take the (4) 30mm shims and put them right of the base plate just right of the (5) 16mm face shims that I moved, along with the odds 29-19mm. so it should look like:

Valve

(12) 30x.10's (removed 4)

(1) 28x.10

(1) 26x.10

(1) 24x.10

(1) 22x.10

(1) 20x.10

(1) 18x.10

I believe this is called the crossover, no gaps, just start ascending with the 19mm

(1) 19x.10

(1) 21x.10

(1) 23x.10

(1) 25x.10

(1) 27x.10

(1) 29x.10

(4) 30x.10

(5) 16x.10

Baseplate

Is it OK that the (4) 16x.10 face shims are touching the baseplate, and then the (4) 30x.10's to the right of it followed by my decreasing odd's(29-19)??? Or should i put them right at the crossover?

This is fun, from what I understand: Taking the (4) 30x.10's off the face creates easier deflection right at the beginning of the flow through the valve for low speed, then subtracting the odds frees up the High speed hits. Everything passed the crossover to the baseplate does nothing. I don't know what the base control face shims do, but im removing per advice thanks!

[MRW]

Thanks, this is cool stuff.

Valve

(12) 30x.10's (removed 4)

(1) 28x.10

(1) 26x.10

(1) 24x.10

(1) 22x.10

(1) 20x.10

(1) 18x.10

This is not a crossover. The stack below the 18mm is just being used as a "spacer" to keep the correct distance (according to Showa) between the valves face shims (30`s) and the "base plate"(.035" +-)

(1) 19x.10

(1) 21x.10

(1) 23x.10

(1) 25x.10

(1) 27x.10

(1) 29x.10

(4) 30x.10

Baseplate

(5) 16x.10

Remaining shims from Base Control Valve stack in they same order as they were before you removed the (5) 16mm and placed them on "top" of the stack ........."under" the Base Plate. You are just doing the same thing you did with the 30mm shims but....doing it on the Base Control Valve side of the "base plate" using 16mm shims.

This is fun, from what I understand: Taking the (4) 30x.10's off the face creates easier deflection right at the beginning of the flow through the valve for low speed, then subtracting the odds frees up the High speed hits. Everything passed the crossover to the baseplate does nothing. I don't know what the base control face shims do, but im removing per advice ? thanks!

Here .. I did some editing above on how your stacks should look.Sorry if I confuse:bonk: ?

The BCV is an anti-dive device conjured up by Showa that works good on MX tracks but not so good in the woods IMO.

You gat it!! Nite Nite it`s 140am!!

[jeddclampette]

I thought the BCV came about to address the negative effects with the 4S engine braking , not necessarily from MX'ing.