Any idea to take apart forks?

KiwiBird

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#2
This was posted by Jeremy earlier - although you forks differ slightly the instructions will cover your forks with only minor tool differences. These instructions also cover the shock.

Instructions for 4616 KYB shock rebuild and valve installation:

Disassemble shock completely:

Remove spring:
-Spring removal can occur by loosening the preload washers on the shock
body buy using a soft drift to loosen the lock spanner and then hand
turning the preloading ring. For speed and ease we recommend that a
spring compressor be used.
-After spring removal inspect shock for leaks and wear.
-Prepare the shock for easy cleaning and rebuilding by reducing
compression and rebound damping to full soft.
-Using a large radiuses punch remove the seal cap by driving it off the
body gently. Tap from both sides to ease the strain.
-Remove the nitrogen charge.
-Using a seal head driver depress the seal head and expose the circlip
-Using an appropriate circlip remover remove the circlip.
-Remove the compression rod by gently rocking the assembly out of the
body, and dump the oil in the piston side of the body.
-Using a bladder driver press the bladder into the body far enough to
expose the circlip. –Remove the circlip and remove the bladder using a
removal tool. Dump the oil in the reservoir side of the body.

Shocks without high and low speed range adjustment.
-Using a 7/64 drill into the peens that are centered on the adjusters
OD. (The peens crush the first few threads into the body and will gall
the adjuster and body during removal.) The depth; should be about 2
threads into the body. Any farther and the o-ring can be penetrated.
Conversely if too little is removed the peens will not be removed, and
damage will result in disassembly.
-After removal take a moment and debur all drilled edges.

Shocks with high and low adjustment.
-High and low range adjusters can be removed without drilling the peens.
Simply use the appropriate remover available from Scott’s performance.
-After the adjuster unthreads, the cap will come out but the actual
valve will remain in the body tube. Firmly grasp the end of the
adjustment jet or stem flats and rock the valve out. Don’t twist or slip
with the pliers, as it will distort the jet.
-The body will have peen marks in the mouth of the adjuster; these bumps
must be removed with a subtitle tool. (We use a porting tool equipped
with a sanding cloth) The goal is to remove the high spot only. If you
go past the normal angle the o-ring will squeeze out during reassembly.
-The washer that serves, as the high-speed tensioner should be placed
flat side towards the valving and curved side towards the spring during
reassembly.


Internal component disassembly:

Valving.
-All KYB Shocks have a nut that is stamped on the top edge. You must
remove this stamp to safely remove the nut.
-All KYB shocks can be ground off flat excluding some early model CR/’s
with out common bleed. These shocks had a 44mm body, and can be
identified by the brass plug at the top of the shock shaft.
-Prior to grinding the rod take a moment to plug the end of the rod with
a dab of grease to prevent chaff from entering the needle valve.
-When grinding the nut off the end of the rod take time to make sure you
have setup a suitable holding method that will prevent the nut from
chattering on the wheel. Strive to produce a flat, square and attractive
finish using precise placement and rotations of the shaft. Cover the
seal head with a cloth to prevent chaff from entering the seal head.
-Grind down to the nut face; after the wheel has made light contact to
the nut face you should be able to remove it. Lightly unthread the nut
if you begin to experience resistance tighten the nut back down and
continue grinding a small portion more.
-Using a debur-polishing wheel finish the nut face and edges.
-Using a valivng skewer unthread the nut and valving and place on a
skewer for washing and inspection.
-Radius the nut face as if it was the first thread. After radiusing the
first thread debur the internal orifice using a deburing tool. Blow the
grease and chaff out using a blast of compressed air.
-Wash your valving out using solvent and compressed air. Lay the valve
stacks out in order on a clean surface. I recommend that you write the
dimensions down of each washer and its order so if mix something up you
can restore it to original spec.

Inspection of parts:
-Clean all components in clean solvent and then dry with compressed air.
Lay all parts out on a very clean surface in good light. We recommend
SafetyKleen brand solvents as they will not harm components, and provide
excellent cleaning.
-Check the piston bore of the shock body for wear by measuring or
visually using reflection angle check for low spots, wear, etc. If the
body has a wear issue with the hardcoatoing you will see discoloration
where the piston has worn through.
-Check the piston band by placing it back on the shaft with a nut and
sliding it into the body. The band should compress and provide a
significant stiction to the body wall. If it is lose, or moves too
freely then the band and o-ring should be replaced. Simply slice the old
band off and install new o-ring and band.
-Check the bump rubber for cracks, or disintegration
-Check shaft for chrome wear or imperfections.
-Check seal head for bushing wear, or scoring.
-Check bladder for wear, stresses, or imperfections.
-Check piston for any metal chips pressed into valve face. Using a
scotch bright pad polish the face lightly but don’t surface. Most 46KYB
pistons are slightly dished to promote seal. When the piston is surfaced
this dish is removed and the shock will not perform exactly as it used
to.
-Replace any components that are worn.

Assembly of the Active compression and rebound valving.

-Install the spring retainer, bump rubber, bottom out plate, using a
seal bullet, and install a well-greased seal head.
-Install the valving components on the shaft stem add a drop of blue
loctite to the threads. Tighten the nut down firmly but do not over or
under tighten. If you’re revalving build the necessary components and
stacks.
-Place the compression aside for a moment.

Installing internal components:
-Place the body tube upside down in a soft-jawed vise. Lightly grease
the threads to help prevent any galling during assembly. Grease the
threads and o-rings of the adjuster. Turn the adjuster into the body.
Once the o-ring has cleared the body tube pour oil into the reservoir
side of the body tube to initiate flow through the compression adjuster.
Taping on the top of the reservoir with a cupped hand will cause enough
pressure to force oil into the body side of the shock. Once you have
fluid on the body side lightly tighten the compression adjuster into the
body. This rotation will help eliminate air from the body of the
adjuster.
-After the adjuster has seated pour more oil into the bladder side of
the body. Rotate the body as it goes into the body, Oil should spill out
over all edges to prevent any air being caught in a pocket.. Place the
bladder into position, (With reference to the Schrader position.)
install the circlip.
-Charge bladder quickly to 100 PSI or so, then remove 30% of the charge,
by holding the Schrader down a second.
-Place your assembled rod into the tube and run it through the travel
until you have a minimum amount of air in the circuits and valving.
(Some recommend hitting the clevis with a soft mallet but for KYB shocks
we typically don’t do this.) When bleeding don’t pull to quickly on
return as you will create a vacuum behind the piston. Also keep the
fluid level up in the body tube to prevent the rebound ports to go above
the fluid level.
-Once the shock piston has been bleed place the rod near the top of the
shock. Add fluid and release the air simutaionsouly. Keep the fluid
above the rebound ports, and continue releasing air until you have no
charge on the shock bladder. Pull the rod back up to the highest point
possible without going above the oil line. Top off with fluid and
install the seal head. Release pressure on the bladder as it fills the
body with excess oil.
-Install the circlip and bottom out plate. Make sure the plate removal
holes are 90 from center so to make them easy to access when servicing
shock again. Install using a soft mallet. (We recommend a plastic
mallet..)
-Charge the shock with 120PSI of clean air.
-Place the shock up right with the lower mount in you vise. Run the
shock through full travel 4-5 times. Check for feel, and inspect all
seals for leaks.


Final bleed for bleed bolt equipped shocks (KX’s RM’s):

-Make sure the rod is fully extended.
-Tighten compression adjuster to full tight. (Peens should align)
-Place the bolt in the position so its internal position is at the
highest point.
-Reduce all bladder pressure to zero. (If you want it’s best to remove
core.. or you can simply hold valve in during bleed, to allow
atmospheric pressure to expand bladder to full size.)
-Open bleed bolt and let all extra fluid to run out.
-Reinstall bolt, and Schrader core.
-Charge shock with nitrogen.
-Inspect for any leaks.
-Install spring and set preload.
-Set clickers

Final bleed for non-bleed bolt equipped shocks. (YZ’s)

-Make sure the rod is fully extended.
-Place the compression adjuster in the highest position.
-Reduce all bladder pressure to zero. (If you want it’s best to remove
core.. or you can simply hold valve in during bleed, to allow
atmospheric pressure to expand bladder to full size.)
-Open the adjuster and let all extra fluid to run out.
-Reinstall adjuster (tighten till peens line up.), and Schrader core.
-Charge shock with nitrogen.
-Inspect for any leaks.
-Install spring and set preload.
-Set clickers


Instructions for 2832125 valve installation:

Disassemble forks completely:

Valving components.
-Remove fork cap.
-Remove bottoming bump components.
-Cup
-Compression plate
-Elastomer
(Note 2001 models have Teflon inserts under fork cap.)
-Remove spring.
-Taking a 14mm Allen socket (Impact style) and a impact wrench remove
the base valve assembly. (Apply downward pressure against the fork rod
using a clean towel. This insures that the valve is moves outward as
apposed to the valve pushing the fork cylinder out.) Use short bursts
and not long durations of RPM as this can damage the components.
-Remove the fork cylinder.

Seal and tube dissembnly:
-Using a subtle blade (Flat but small screw driver) remove the dirt
scraper. Don’t pry as it may mar the forks appearance.
-Using a smaller blade remove the circlip that holds the seal in place.
-Heat the seal carrier or the portion of the tube that has a unanodized
finish uniformly so as to facilitate easier bushing removal with out
damage.
-Using quick but not forceful hits drive the tubes apart. (Speed is more
important than force and never yank at the end of the stroke.) Use the
quick momentum to drive the tube off. Failure to do as described above
often results in bushing damage.

Internal component disassembly:

Fork cylinder: The 3228125 Bumper style fork requires that the stakes at
the head of the cartridge be removed before the active and rebound
valving can be modified.

-Using a 6mm 2 flute end mill, mill the stakes out of the cartridge. The
stakes can be identified as 4 dimples at the head of the cartridge or
the CV (Cylinder Valve) (It is best to use an end mill because the CV
has very thin walls. A drill with sufficient diameter to remove the
whole stake will often pierce the CV walls before the edges of the drill
have removed the stake.) Mill to 1.8mm depth. It is very important to
keep the edge of the mill just bellow the bottom edge of the stake.
Failure to do this will result in the last few sealing threads to be
pierced and will cause chronic leakage and hence poor fork performance.
Be careful to clean all parts thoroughly of AL chips created by the
machining. (The chips like to migrate into the CV exit and plug the
valving.)
-Using the light to moderate heat warm the area around the now milled
stakes. This is important to relive tension and locking agents used in
assembly from the factory.
-Using the CV holder place the components in a vice.
-Using a appropriately sized screw driver or round stock turned to the
hole diameter, unthread the cylinder form the CV. Uses a back and forth
unthreading technique to help prevent thread galling.
-The nut holding the valving components has been staked from the factory
and needs to be ground flat past the edge of the stake to remove the nut
and separate the valving and piston. (Prior to the grinding process pack
the orifice with grease to prevent grinding chaff from entering and
being lodged in the internals.)
-After removing the stake the edge of the nut needs to be radiused of
its metal bur that develops during grinding. (This bur may come free
during fork use and causes numerous problems.) A polishing wheel such as
cratex works very well and leaves an excellent finish. Be very careful
to maintain proper shim and piston orientation during removal. Also note
that may times small spacer shims are placed under the post spacer, or
valve these are easily misplaced and will dramatically impact fork
performance.
-Now that all the components are free of the stem radius the first
thread to prevent thread wear during reassembly.
-The passive valving (base-valve, or foot valve) needs to removed. The
nut can be just turned off on these model forks. After the nut and
valving has been removed you will need to radius the first thread in the
same manner as the active stem. Proper orientation must be maintained to
insure the components are assembled properly.
-Wash and clean all components thoroughly before proceeding any farther.

Assembly of fork tubes.

-Place the axle bracket in a vise and firmly tighten down.
-Placing a bag over the tube lube the seal and install the dirt scraper.
(Remember that seals always work with pressure so if orientation becomes
unclear use that as your guideline.) Install the circlip, oil seal,
backup washer. With round edge toward the seal. Bushing outer and then
bushing inner. (After the oil seal is installed remove the plastic bag.)
-Use a 46mm seal driver to drive the seals and bushing into the seal
carrier. Install the circlip and then install the dirt scrapper.

Assembly of the Active compression and rebound damping.
-Build the stacks specified and then install them on the stem. By very
careful not to misalign any washers or components as they could be
permanently damaged by doing so.
Double check all components for proper assembly.
-Tighten the nut down after a small amount of blue loctite has bee
placed on the threads. Make sure that the nut is not lose or over
tightened, clean all components with compressed air to blow off any
extra loctite.
-Put the rod and CV back into the holder and apply a small but uniform
amount of blue loctite to the CV threads. (This will serve as both a
lubricant and a sealant during reassembly and use.) Tighten the Cylinder
down. (Very tight)

Assembly of the Passive compression valving.
-Install the valving components on the base-valve stem add a drop of
blue loctite to the threads. Tighten the nut down firmly but do not over
or under tighten. If your revalving build the necessary components and
stacks.

Installing internal components:

-Place and align the fork cylinder in the tube. Grease the base-valve
threads and piston o-rings. Using downward force to the rod place the
base-valve in the axle bracket and tighten the valve. Once the threads
have been engaged use your impact wrench to finish the job. Tighten in
firmly, using quick short bursts. Long and high speed rotations are
damaging to the components.
-Place the fork upright and fill with fluid. Let the fork oil settle
into the gaps between the tubes by refilling every few moments or until
the level stops falling. At this point thread the fork cap on the rod 1
to 2 turns and lift both the outer and inner tube to full ht allowed by
the cap. Quickly compress the fork full travel. That should initiate
fork bleeding. Refill the tube and bleed the rod by stroking up and down
until the action becomes consistent and smooth.
-Set the oil ht by measuring from the fluid level to the edge of the fork tube.
-Double check the jam nut tension on the rod. Do this by firmly holding
the rod in your hand and tightening the jam nut down as hard as
possible. (Do not ever grasp the rod in anything other than a holder.)
-Extend the rod completely and lay the fork over to a 45 degree angle.
Quickly and precisely slide the spring down over the rod. Place the fork
cap and bottoming components on the rod.
-Holding the rod with your thumb and index finger tighten the cap down
till it seats on the top of the rod. Then insert a thin 17mm and tighten
jam nut up to the fork cap. Firmly tighten jam nut to fork cap.
-Bottom fork cap to the tube but do not tighten. The top triple clamp is
responsible for keeping the cap on.

Check for improperly placed rods during rebound clicker setting. Compare
the depth of screw in fork cap left and right when rebound is full hard.
(This is a quick test.)

Reset your clickers and enjoy!
 

KiwiBird

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#3
I remember your CR is 93? If so you can benefit from fitting the Race Tech bushings for Showa 43mm forks which have a different "floating" design which reduces the binding when the bushes pass the lower triple clamp.
 
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#4
I take that pretty big answer as a yes. If i would find any worn parts, what pricerange can i expect for a change?
 

KiwiBird

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#5
Hi Pyro, just got back from 3 days of riding. Try Race Tech - that should give you an idea of prices in the US, don't know if getting them from US or one of the RT dealers in Europe would be cheaper. I'd only recommend using RT for the unique Showa bushings they make, the rest of the bushings and seals are stock Honda. Check the specs on your spring length and preload accordingly to make up for any sacking of the springs.

Have fun
Kiwi
 
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#6
I began to take apart the forks today. I didnt understand a thing of the instructions!
Nevermind, i have come so far that i have removed five items. The cap, spring, a thin tube, a little spring, and another thing that i dont know what its called. Here starts the problem, i cant come any futher. I want to remove the big thing thats on the outside of everything. How do i do that?
 

KiwiBird

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#7
Pyro, first get to know what everything looks like.Exploded view of fork sort of like yours.

It sounds like you have the cap, spring, rebound adjusting rod/spring/rebound needle apart. Some of these aren't really shown on the link as the forks are diff from yours.

To remove the cartridge from the tubes you will need to undo the base valve which is number 14 on the bottom of the forks, which secures the cartridge. I think it is a 22mm? Ideally you should have a cartridge holding tool to stop the cartridge rotating when you undo the bolt but I doubt you do so there are a couple of different methods to use. Put the springs back in and do up the cap and then turn the forks upside down and compress them as much as possible - this will put friction on the cartridge and stop it from turning, then undo the 22mm bolt. I put the axle in the fork and then clamp the axle in the vise (with softjaws or a rag) and then put a block of wood under the cap (forks upside down). Take your time doing this or BAAAAD things can happen.

Once you have the bolt out undo the cap again and the cartridge should come out. If you are going to remove the bushes and seals you need to know that a seal driver is required to replace them - YOU HAVE BEEN WARNED!! You may need to go to a shop to have them replace them or if you are REALLY CAREFUL you can do it with the old bushes.

You should now remove the dust cap on the tubes (31) and then the spring clip (15). Boil 2L of water and then pour the water evenly over the outside area where the bushes are (where the clip was) to help the next step. The bushes are pressed in and you need to extend the forks, like the wheel is dropping away from the handlebars, repeatedly to get the 2 tubes to separate. Use about 2-5 kgs of hand force. They will slowly come apart - repeat the boiling water if necessary.

Once apart note the order for later reassembly. Remove the bushes, seal and wiper. Note which way the seal goes - this is very important!!!! Clean everything with solvent and lay out for reassembly.

I'll leave off there till Monday as I'm off riding again.

Have fun
Kiwi
 
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#8
I think i know what you mean. But i think it can be some problem to remove the nut on the bottom. Because the walls around use to be smashed so you cant get the nut off, i dont think it is that smashed on my current bike but i remember it was on my old yz. Guiss i have to figure out how to get grip on the cartbridge that spins and see if i can get the nut out or i may have to fix the walls.



Thanks for the help kiwi bird i let you know how it works out!



BTW why i dont know the name on many parts is not because i dont know what they are, its just that i dont know the english name for them, because i have learned english in school and as you may understand we dont talk motocross there :D
 
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#9
I managed to demount the whole fork. But still doesnt understand how to remove the spring on the shock. I also noticed that it sounded like oil in the shock, its supposed to be a "gas only". Maybe its liquid gas or have someone put oil in it anyway? How much can i expect a gas refill to cost?
 

KiwiBird

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#10
Greetings Pyro, are the forks completely apart now?

The rear shock is filled with oil and has, in the resevoir, a bladder (balloon) which is filled with gas. The bladder separates the oil and gas.

To remove the spring you must loosen the adjusting collars on the body and then when the spring is without tension remove the retainer at the clevis end. I don't know what shock you have so there are 2 different designs. One has an opening in the collar which fits over the shaft - that should be obvious. The other uses a circlip which stops the outer piece from sliding up over the inner piece. I really wouldn't recommend you change the shock oil unless you can see someone do it first - it'll probably cost you about $50 - 100 to get the shock serviced, depending on you local dealer.

Kiwi
 
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#11
Yeah the forks are completely apart.







The shock i havent really tried to take apart much cause i only see one way to do it and that way i think oil will leak out. I have changed oil on some older shocks that was oil only. So i guiss its a little differece now.







I dont know any english words on the shock either, other than spring :) so i dont understand really what you mean. I only see one screw i can remove and its the one where i have the "clicker". Or can i remove the steel thing which holds the spring on the bottom and on that way take apart the spring?







Can i change oil and then just let the dealer rechange the gas? Do they change gas with the valve that looks like the one you fill your tire with air? or is that one for air aswell?





Well i think i do as i use to do when im not 100% sure what to do - try. That have always worked so far. I use to understand how things work when i see the parts :)
 

KiwiBird

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#12
Ok - loosen off the adjusting collars on the shock so the spring is loose and then remove the collar (ring), which rests against the spring at the end with the rebound adjuster. The collar will either have a gap that fits over the shock shaft or it won't.

If it has a gap, push the bottom out bumper down the shaft so you can remove the collar.

If it has no gap, the same part is 2 piece, the piece against the spring is separate from the part closest to the shaft - clean it thoroughly and you will see the join. Hold the bottom out bumper and carefully hammer round the ring edge down towards the spring - the 2 pieces should separate and you will see the wire ring which you will remove.

You can change the oil throught the compression adjuster AFTER YOU RELEASE THE GAS PRESSURE with the valve you mentioned. I'll give you details when you are ready.

Once you have changed the oil and bleed the shock you can get it recharged with nitrogen (not air) at a dealer.

Did you see the special bush for your fork at the Race Tech web site?

Are we having fun yet? :)

Kiwi
 
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#13
I see, i havent done anything yet, been busy repainting the frame and other.

I noticed that it wasnt any gas left when i tried to release it through the valve, guiss that can explain the bad performance. Then i can also guiss the oil is old.

So i will change the oil and recharge nitrogen. Also i dunno if i need to change spring, cause it had zero free sag but okay race sag. I guiss if i loosen the spring enought to get right free sag the race sag will be too much. If i find out that i need a new spring how do i find out what hardness the one i have is? I dont think its stock cause im only 60kg and it feels pretty soft and using all the travel quite easy.

No i didnt see the bush at racetech, tell me about it.

Pretty fun but not quite as when the bike is running again!
 

KiwiBird

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#14
The bushing from Race Tech is here . It's only for Showas which I think your 93 CR250 has.

Sounds like you have a very soft spring with no free sag when you have good (100mm or so) race sag - I'll check when I get home for what the stock spring is. It's very difficult to work out shock spring rates without a machine. Does the spring have any markings on it, like paint dots or writing?

The lack of nitrogen will make the shock feel very soft, question is - why did it leak out? You may have a ruptured bladder, was there ANY gas in there?

Kiwi