fork leaking oil...

After riding this past Sunday I was loading my bike up in the truck and noticed oil draining down my fork. Has anyone every replaced the seal and if so, just how hard is it to do?

try this first: remove the fork guides & take a business card and slide it past the seal and work it around the fork several times... pulling it out often to try to drag dirt out that could be letting oil get by. Sometimes this prolongs the obvious for a few weeks.

Otherwise, get your parts first.

you need:

(2) 5ET-23125-L0-00 METAL, SLIDE 1

(2) 5ET-23171-L0-00 PISTON, FRONT FORK

(2) 5ET-23145-L0-00 OIL SEAL

(2) 5HD-23144-L0-00 SEAL, DUST

(2) quarts of 5wt fork oil

you need a 14mm allen wrench socket to impact out the base valves.

It shows you and explains in detail how to do this in the manual. It's scary the first time... but it's not something you can't do if you have average mechanical skills. Examine your lower fork legs closely and make sure there are no knicks or burrs raised up from a rock striking them. These can cut seals. If you find a burr, wet sand it lightly with 400 grit emorycloth. Lay everything out in order as you disassemble the forks, and only do one fork at the time to avoid confusion & mixing up parts. Make sure you use a plastic grocery sack over the top of the fork when you slide the new seals on. It protects them while going over sharp edges. It shows this in the manual. DO IT! It's important. Take your time and you can do it. I don't think nothing of it, now. I wince when I see people take their forks off & give em to somebody to put seals in for em. I see dollar bills flying away... lol. Some of those guys will reuse the old bushings. I always replace mine. ALWAYS. The parts should be around $100 or less with oil. Your labor is free to you, and only you can treat them like they are your own (cause they are) Good luck! You can do it! :)

[ May 07, 2002: Message edited by: Fireball ]

Hey Shane,

Replacing forks seals are relatively easy (I have done about 15-20 times for my bike(s) and friends bikes). If you run into a bind give me a call at 281-482-2522 I live in Friendswood and would be happy to help you if you need it! The business card trick will work for a long time if you clean them really good.

If you need to buy new seals goto a Honda dealership and buy 96' CR250 seals and dust seals (they come in a kit) and are 1/2 the price of Yamaha OEM seals and are better quality (I said the seals not the bikes you CR450 guys :) ). Good Luck,


BTW have you heard about Skeeters MX in Alvin opening up...I went out there yesterday and it is a killer track!

Hey Garret,

Hey Garret, Factory Connection sells a kit also. They label it as an "upgrade", the seals are slightly bigger than OEM 426's and have lasted for over 8 months now, versus less than 4 with the OEM ones. I also do that dust seal trick now, which I'm sure has helped tremendously.


I live in an apartment here in Clear Lake. I keep our bikes at my parents house up in

New Caney. It really sucks because I have to drive up there and get them when we ride. So I won't be able to work on it till this weekend.

I went out to Skeeters Saturday and went to Rio Bravo Sunday.

I use to race at Rio Bravo during the 80s and raced hare scrambles and enduros with TRH. I got away from bike riding for about 10 years and I am just now really getting back into it. (I have more time now, since I am I am still rusty and can't ride like I once did, but I am having fun. Maybe we can go ride someday, I am faster in the woods. Do you go to Sam Houston National Forest much?

We ride at New Waverly every now and then (it is hotter than hell in the woods in summer time)...but I prefer MX tracks. Im sure you ride Splendora alot since it in 5 miles from New Caney? I will probably ride Splendora on Sunday (I might race at Skeeters on Mothers day).


yamaha seals are garbage.i had problem with forks seals going bad.i had to change the every 3 or 4 months.i switched from using yamaha to kawasaki forks seals [97-01kx500 are same size as wr,yz]its been a 16 months since i change and still no leaks.the kawasaki seals are made of different rubber[poly?]the only thing is they are $15 each compared to $5 yamaha seal.

Here is a procedure for total rebuild of the late model YZ fork.

You can just seperate the tubes and slam in new seals, but you will be leaving all the crud in the pistons, not to mention the face shims that will need changing on the midvalve compression shim stack. Its easy to just change the seals, but to do a thorough teardown, inspection, and rebuild, well, thats another story.....

The main website gets credit for this having this info available.

Instructions for 2832125 valve installation:

Disassemble forks completely:

Valving components.

-Remove fork cap.

-Remove bottoming bump components.


-Compression plate


(Note 2001 models have Teflon inserts under fork cap.)

-Remove spring.

-Taking a 14mm Allen socket (Impact style) and an 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 an un-anodized 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 to1.8mm 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 an 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 be 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. Be very careful not to mis-align 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 height 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!

I am currently working on my forks on my KLX650. I ran into the problem with the allen wrench (don't have one that big) for the valve assembly as well as the fork cylinder holder (don't have this, either). Do I absolutely need this tool, or can I get by without it? Thanks.

After riding this past Sunday I was loading my bike up in the truck and noticed oil draining down my fork. Has anyone every replaced the seal and if so, just how hard is it to do?

The first time you change fork seals can be very time consuming but not hard at all. Use the owners manual and follow the step-by-step instructions. I made my own fork seal driver and damper rod holder out of pvc pipe. You dont have to buy Yamaha brand fork oil either(its expensive). I use Belray 5w and it works nicely. A dealer near me sells the seals and wipers as a set so thats convenient. Sounds like you asked about changing just one seal, but I think its best to change both seals at the same time. Anyone disagree?

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