fork oil?

I have a 01 426 and the left fork seal is shot. I have never worked on my suspension before so this is a learning experience for me. My question is, what kind and weight of fork oil to run. I haven't done anything to the right fork so it still has the stock oil in it. I don't know what the stock oil weight is and I don't want too have the forks uneven. Also I don't want the fork oil height to be off. should I replace the oil in the right fork too? Help my out here guys.


Definitely replace the oil in both forks at the same time. Also it's worth the investment to get a fork oil level kit. It's basically a syringe with a long strait tube and a metal ring that clamps onto the tube. You set the tube to the height that you want and then you suck the extra oil out with the syringe. You can make something similar yourself, just be sure to have something of this type to set the oil level.

As for the oil, I personally use the Yamaha Suspension Oil 00. It's expensive, but it's the stock oil. I'm sure any name brand fork oil will do if you don't want to spend that much, just ask for the stock weight if you want to keep things the same.

Also when you're done, don't forget to put some lithium based grease behind the fork dust wipers to lubricate the seals. The manual is very good, have it with you when you work on the forks and you should be OK.

I agree with Thumpalot in both areas.

I tried using 5wt 3.5wt

I just replaced the seals in mine and the oil is the yamaha 01. I can honestly say It really made a differance. is the cheapest I have found...

and invest in soem seal savers

There pretty clean looking once on...


Buy the long sleave for 21 bucks you can make three pair out of them as opposed to 16 bucks for one pair of shorties

[ July 18, 2002: Message edited by: E.G.O.**** ]

How much oil should one fork hold? Once I have a bunch of oil in it, what level should I measure it too?


A very good investment is a seal driver. You will need one to EASILY install your new fork seals.

You can remove your base valve using an electric/pneumatic impact wrench and the correct size ALLEN HEAD socket. If not, You'll need a cartridge rod holding tool.

I use a turkey baster with clear tubing to set oil height. With the long tubing, you can have the turkey baster squeeze bulb down. I add oil, pump the forks, check level with a ruler. You can draw out any excess oil with the baster.

The thing about the correct suspension tools is without them, you are screwed. DO NOT go to a dealer for simple maintenance like this. It is just money out of your pocket. Spend the $$$ on the right tools, and you will ALWAYS be set.

Congratulations on stepping up to the plate on doing this yourself!!. :)

FYI: has a NEW STYLE of seals for our bikes. The seal is thicker (taller) than OEM. It will last longer. With the seal you MUST purchase their thinner washer. I shipped a set of these seals/washers to a fellow ThumperTalker in Sweden(?) ~6 weeks ago. The whole thing came to $45.00 for seals and shipping to Sweden. :D

Dont waist 40 -50 too 70 bucks on a seal driver, You can build one for 2 bucks

Go down to ACE, Home Depot or any hardware store that sells PVC.

Pick up a 3" Black PVC Connector or a 3" toilet flange

Cut in Half This then fits around your fork tubes.

Use a 3 oz rubber mallet to tap the PVC down until seated.

I will post a pic of my 2 buck tool.

motoman also has a pic (Crude) but still the same concept

@ loo under tech articles

[ July 18, 2002: Message edited by: E.G.O.**** ]

Can anyone give me a better explination (bad spelling I know, I'm right up there with E.G.O.)on how I am supposed to use the seal drive. I am going to go with the PVC, I can spend $60 on a hell of a lot of better things than a seal driver! But I still don't under stand how to use the tool. E.G.O. said use a rubber hammer. How do I hit it if it is on the fork tube? Little weed eater doesn't understand! :)

I almost forgot! On the bottom of the fork, for the bottom thing whatever it's called. What size allen wrench do I need? Looks like a 15mm or so but I don't have anything that big. I will need to buy some new tools. thanks guys

[ July 18, 2002: Message edited by: Dansgarage ]

Sorry should have splained a little better

Place the PVC around the fork tube

I used tie raps top and bottom to hold it in place just cinch the ties.

with the small 3 - 5 oz mallet you can let the mallet slip up the side of the tube with no worry of scratchs.

Just firmly tap the pvc in side to side or circle motion around the tube.

Keep firm pressure downward with your hand holding the pvc while tapping the seal down

Grease the seals outer rim , and slip some grease inside the seal surface area of the tube (NOT ALOT) just enough to help with it going in..

Just take your time and make sure the seal is driving in evenly, once it is seated you will know, you can give it a few good raps to make sure its seated all the way around....

Once I hade the seal in I placed a far amount of the white lithium greas in between the seal itself and the dust seal....

Hope that helps

Sorry the dust seal is a breaze to put in just slide that on and use the same method with the mallot to drive it home

Dont forget the Clip between the dust seal and the main seal

[ July 18, 2002: Message edited by: E.G.O.**** ]

Thanks E.G.O., Thanks guys! I now feel that I am on the right path to Fork Jedi-ism. May for fork be with you! HAHA, I crack me up!

Yamaha 01 IS 5#.

Don't let anybody say it isn't BECAUSE IT IS!! Honda's SS-7 is also 5#.

Bel Ray makes a 5# oil suitable for USD/cartridge forks. It will specifically say this on the container.

My 99 forks each took 500cc to reach MINIMUM level. You can always put in 500cc per leg, and add oil through the vent plug in the top of the forks later. If you are bottoming and you have to crank up your compression clickers, it's time to add oil!

Be sure to follow your instructions about adding (half the amount?) of oil then PUMPING your forks. The oil has to be pumped up into your cartridge rods. Then you can add the rest of the oil. Otherwise, you will be spilling oil onto the floor, saying "&%$#@!?"

I was running Belray 5 and drained that and placed yamalub 5wt in it. I just rebuilt the forks and spent the moola on the Yamaha 01 oil. Honestly the forks are workign great, adjustment is easy and it feels better.

Maybe it is me, But I would opt to the 01. But the 5 is fine, and lots cheaper...

[ July 20, 2002: Message edited by: E.G.O.**** ]

I use Silkolene 5wt. Works fine. These forks are very "tunable" by raising or lowering the oil level. Just make sure you stay in the limits in the manual. Did you try cleaning the seals with something like a film negative? And bleed the air off? I'm still on my stock seals on my '00 after 3 seasons of moto and I'm a big tubbo...

There is a description of replacing the fork oil in 'Fork Oil 101' thread on the 250F forum.

Good luck,


what is a "film negative"? I know your not talking about pictures!!! I had to put that in before some smart A** did. Degreaser, cleaning solvent, isopropyl alcohol or what?

I do have a couple more questions. What weight fork oil should I use, I can only find bell ray 5wt here on the island. I don't want to have to wait two more weeks trying to get something sent up to me. Will the 5wt work. I know that my manual calls for yamaha 00 or 01 but what weight is that? Does the weight actually have anything to do with dampening or just oil height in the fork? Does a higher wight just stand up better in warmer weather or vise versa? How much oil will one fork tube take? I have two quarts but do I need more? I'm lost!

[ July 20, 2002: Message edited by: Dansgarage ]

Film negative is exactly what it is. I use a real thin plastic id card to swip my fork seals when they start leaking. I will also spray with carb cleaner when I'm swiping them. Sometimes it can take a while till they get clean but it definetly ain't as long as changing the fork seals. I wasn't about to bust out the $30 or so dollars for a oil level guage so I bought a small adjustable square from home depot for $4 with metric readings on it. I works great. The only thing I wish I would of done was instead of spending the $60 on a fork seal driver was use that PCV idea instead. I'm pretty sure that the Yamalube 01 is 5 weight also.

I should have explained meself better. Yes, 35 mm film negative works best because it forms to the shape of the fork tube and is thin enough to get under the seal. Just use it to scrape all the crud out from under the seals. I'll bet a big majority of leaky fork seals are just dirty.

Ok so you were talking about picture negatives. Don't I feel like the jack A**! :) OH WELL!


The seal savers work great if you want to keep them clean all the time..

Ok I have another question. I went to take apart the base valve and the damper rod. The damper rod internals came out without the housing, not the base valve and the damper rod with it's housing. I put the damper rod back in, retighten and tried to take it apart again. No luck. So what do I do now? How am I supposed to get the base valve out? thanks for the help guys

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