WR250R Rear Shock Rebuild with Pics

I'm sure somebody has posted a rebuild on the WRR shock before, but I was unable to find it. The process was actually much easier than I was led to believe. So I took it upon myself to take pics as I dove deep into my rear shock rebuild!

I recently purchased my WR and the suspension utterly blows, from what I've been reading that is a common opinion WR owners share. I'm 6'2" and weight about 200lbs when fully geared up, when I sit on my seat the bike sags a ton and the dampening is non existent. My assumption is either the oil inside was bad, somehow was half drained, or was way too light.

Without further ado, the WR removal and rebuild:

Now everything I read on forums and even in the Yamaha tech & service manual (I bought the PDF version message me if you want it) it says to remove the entire rear frame. I don't know why, it was very simple to remove it on the battery box side with some maneuvering.

Step 1) Put it on a stand to re-leave tension on the rear shock, if you don't have a stand...make one haha

Step 2) Remove these two pivot bolts

Step 3) Remove the seat and side panels and prop up the rear wheel 2"

Step 4) Remove the top eyelet bolt and wiggle shock through by the batter box, you may have to move the linkeage below around to allow the bottom part of the shock to move side to side enough to fit


Yay you got it removed with just using a 5mm allen, 14mm, 17mm, and 19mm sockets! Easy enough, takes about 15 minutes
Now to the shock itself

Here's the tool list: 1 Vice, 1 Hammer, 1 Set of Channel Locks, 1 Mountain bike shock pump (if your using air - I'll explain shortly), 1 17mm socket wrench, 1 Flathead, 1 Plastic bike tire lever or plastic rod/ dowel

First things first, you need a Needle type tool for the shock. It's NOT A STANDARD VALVE like most shocks. I would recommend buying a RaceTech bladder piece to replace the "self sealing" rubber this shock comes equipped with. 41.9mm is what I measured to I believe this is the part from RaceTech SMRC 40004. It's $50 but adds volume and you don't need to spend $30 on a nitrogen needle like I did.

Step 1) Remove the air using a nitrogen needle OR any hypodermic needle. Wet the needle with spit or lube, then slowly insert it into the hole on the reservoir cap until air purges out

Step 2) Remove spring
Step 3) Using the flathead, gently tap the base cap off. Keep in mind this is CAST ALUMINUM and very soft, take your time.

Step 4) Using the rubber side of the screw driver, press hard on the reservoir cap. It will suck in until a C slip is revealed...it's tough, but use your small pry tool and pull that sucker out. In fact this is the hardest part of the rebuild!

Step 5) Once you got that clip out, slowly compress the chock together until the pressure pushes that cap out. Using your channel lock gently pull out the bladder and cap. Clean both and if you got the RaceTech cap, insert it in the bladder.

Step 6) Now using your hands (maybe with gloves) press directly down on the main seal, it will drop about 5mm exposing a C clip. Using the plastic rod or tire lever (whatever you can find that's not metal) hold that seal and base assembly down until you can get a tiny pry tool in there and remove the C clip. This part was a pain too!

Step 7) Remove the entire piston/ rod assembly slowly. NOTE: I was told by 4 local shops/ suspension specialists this shock was not rebuild-able, obviously it is because there's nothing blocking the piston, shims, and entire piece from being disassembled. Yet another occasion I'm glad I didn't believe a reliable source :/

Note: That is the saddest excuse for suspension fluid I've ever seen...looks like soapy water!
Step 8) Start pouring out fluid. Remove the 17mm nut w/ compression adjust on it. Drain more fluid...

Step 9) Put the compression piece back in (after cleaning thoroughly and applying fresh oil to the seal)
Step 10) Time to put it all back together! Start by putting the bladder and cap back in with the C clip
Step 11) Oil:
I wanted to rebuild the shock to what I would think a STOCK setting would be first, I'll adjust later if need be. So I opted for 3 Wt oil. Shock oil is different from suspension fluid I guess so make sure you buy the right stuff. Knowing what I know now, I would have done 5 Wt.
I poured 240ml in, I used measuring cups while catching the oil that was in there, and I caught about 230ml. The 240ml I put in allowed for full travel and no "hydro lock" nor lack of oil in the system once fully assembled. So I'm guessing it's correct.

Step 12) Unscrew the compression adjuster again VERY SLOW, to let the trapped air out. Just wait until oil starts coming out (catch it in a cup) then re-tighten it and pour the oil back in the top
Step 13) Put the piston assembly back in the body using the same method you used to remove it

Now the Nitrogen Needle and shock pump: I inflated to 160-170PSI

The reason I use the shock pump is because you can get the high pressure you need for free. So you can replicate the amount you want, and also if something is wrong you didn't waste the money filling with nitrogen. The only place locally I can get to fill my nitrogen charges $22!! To fill and deplete nitrogen from shocks...so once you have done your shock and feel happy with how it is set up, THEN have a shop fill it for you.

I actually use air instead of nitrogen. I've used both in shocks before and can't tell the difference at all while riding. I understand larger molecules in nitrogen won't allow as much air loss over time, but how hard is refilling my shock every once in a while with a pump?! It's cast aluminum, which will oxidize eventually form moisture found in air, but I'll pry have 5 other Dual Sports by then.

Look at the mountain bike industry, everyone uses air. All of them same technology (hydraulic based dampening, spring compression, air compression ect) and they all use air. If it's good enough for them, it's good enough for me.

Tips for next time:
Race Tech Reservoir Cap
9-10kg Spring
5 Wt Oil

Feel free to add and/ or scrutinize.
I'll touch base on valving upon request, it's a whole nother ball game when you add valves, fluid, air, and coils together haha

Nice write up on this. I know I will appreciate it fairly soon. I need to do something with the suspension.

Thanks man.

This should get a sticky.  

A few points:

1. This shock is 100% rebuild-able/serviceable/upgrade-able.
2. If you want to re-shim, which I highly suggest, you will need to grind/file the peen off the nut holding the piston on. No big deal, just like every other shock.
3. Oil VOLUME is not exactly important. You always want enough oil in the shock as you are filling up to spill over when you install things. You want enough oil in the reservoir that oil spills out as you put the bladder in. You want enough oil in the body that it spills out when you put the piston/shaft assembly in. The idea is that the shock is 100% filled with oil, and then pressurized with n2.
4. You need to BLEED the shock by moving the piston up/down before you seat the seal head. You COMPRESS the shock quickly, and then REBOUND slowly. This gets the trapped air out from under the piston.
5. I am not a fan of "air", but it does work if you know you are going to be in/out of the shock a bunch tuning.
6. Shock oil should be as LIGHT as possible. The temperature/viscosity curve for oils gets crazy as the weight goes up. You want the lightest possible fluid. If you need more damping, re-shim.

Good work! How does it RIDE?

ac

Does anyone know if the Race Tech reservoir cap will work with the WR shock? I emailed Race Tech and they say they do not have a cap to fit the WR rear shock. Nice write up, I'm going to buy a RT gold valve kit and rebuild my shock.

Didnt race tech tell you you can drill and tap the stock cap and install a 1/8 npt scrader valve?

I did this to mine after the rubber seal the needle goes through pushed into the bladder, you drill and tap the hole the needle goes into.

Biglake wrote:

Didnt race tech tell you you can drill and tap the stock cap and install a 1/8 npt scrader valve?

I did this to mine after the rubber seal the needle goes through pushed into the bladder, you drill and tap the hole the needle goes into.

no they did not, I just asked them if they made a cap. I will drill my cap, thanks.
I just received my Gold Valve kit in the mail yesterday and will rebuild my shock soon

thanks for the tips

Hi guys, I would like to share with you my experience with WR250R Rear Shock disassembly.
To make removing c-clip from the reservoir a lot easier I took my hand miller and made a little groove where I can insert small screw driver.

And I as I don't have mentioned nitrogen needle, I made one from old tire tube valve, needle and a valve cap.
I shortened the plastic part of the needle and grinded it into 4,5-5mm diameter, then I redrilled bottom side of the stem itself so that deedle can be inserted into it. Then I took the cap, cut of the tip for loosening the valve and drilled it though with 5mm drill bit. When assembled, the rubber sealing in the cap seals this all and no gas escapes.

Because I had a feeling I didn't assemble the shock well for the first time I disassembled it several times and I didn't feel comfortable with punching the shock with the needle. Therefore I deciced to replace it with mentioned schrader valve. I got myself an old tire tube, cut the valve, visited my turner and asked him to make me a thread in the shock cap. He didn't have the rigt screw-tap to fit the htread on the schrader valve so we decided to make an M7 thread on the schrader valve and then an M7 thread in the cap. Then I glued the valve in the cap, assembed the shock and visited local bicycle shop to ask them to inflate the shock for me with air. They did it for free.
Yesterday I rode it with this tune-up for the first time and I didn't feel any difference compared to stock. Maybe i I want to I will visit local tire repair shop and ask them if they are able to inflate the shock to 160-170psi.
Here's the result: