fork oil??

Hi guys, just greased up my steering cone bearing and now it works great!

thank you guys for your help. :)

Will need another enquiry from you guys,

what is the nut size on the fork tube?

And can I loosen it without using the impact air wrench?

And what is the oil level, where to I measure it from? I really need detail on this guys.

I'm a totally nerd on this. Can anyone help?

Thanks! :D

Henry, I just got done doing my steering head bearings, fork seals and oil. I'll help all I can.

If you are refering to the Cap bolt on top of the fork its 19mm. If you are refering to the base valve at the bottom of the fork it is a 14mm hex/allen. You'll also need a thin 17mm wrench to get the cap off of the damper rod. I found that a thin 11/16 wrench works as well. Found mine at Sears. You'll also need a turkey baster and about a foot of plastic tubing that fits on the end of the turkey baster. As far as oil goes, the manual says use Yamaha 01. I've heard that Yamaha 01 is equivalent to 2.5 weight, 5 weight and 7 weight. Every dealership had a different opinion... I talked to alot of suspension shops, they also differed in their opinions but the majority agreed on 7 weight specifically, Spectro 125/150 (7 weight).

If you plan on pulling the fork completely apart let me know and I can help with some helpful hints. But, if you just plan on changing the fork oil follow these directions.

1. Before you take the forks out of the clamp losen the Cap bolt (19mm). Loosen it just enough so that when you take the fork off you can still get it off while only holding the fork tube with your hand and just enough so that the oil doesn't leak out if you lay it down horizantally.

2. If you have access to an impact driver and a 14mm allen that it's definately the best way to get the base valve off. Using the impact driver allows you not to have to buy a cartridge holding tool to hold the cartridge from inside while you take off the valve. The driver actually spins the valve off fast enough so that you dont have to hold the cartridge.

You can drain the forks without taking of the base valve but I wouldn't recommend it. It takes forever, you have to constantly pump the cartridge rod up and down over and over to get the oil out of the cartridge. Even then you can't be sure you got it all. Besides you'll find quite a bit of grit and grime just inside the base valve.

Whatever you do, wash the forks out and off with a contact cleaner you are sure doesn't harm plastic or rubber. I use PJ1 Super clean, good stuff.

After you've drianed the oil and cleaned the fork out and off;

1. Follow the directions in the manual all the way up to the point where you first fill the tube with oil.

2. Fill the tube like the manual says, all the way to the top of the outer tube. You'll notice the cartridge rod will be just below the surface of the oil, no big deal, just grab it and pump the rod all the way up and down more than 10 times. You'll notice that while you are pumping the rod the oil level will drop alot, keep the oil level full as best you can, dont let it drop to much.

3. After you pumped the rod and noticed the oil level isn't changing any more tap the tube lightly to get the air bubbles to the top. Let the fork sit for at least 10 minutes so that the bubbles have enough time to get to the surface.

4. After you're sure all the bubbles are out. Fill the tube again all the way to the top of the outer tube. Grab the outer tube and move it slowly upwards, go slow, and just like the manuals says dont raise it more than 7.9 inches. What you are doing here is filling that space between the inner and outer tube with oil. If you do raise the tube to high you may hear a sucking sound, if you do you've just sucked air into that space, BAD! Refill the tube and start over.

5. Now you are ready to measure your oil level. Fill the tube again, if you see more bubbles let it sit awhile more. I checked around quite a bit on what oil level was best and of course heard many different opinions. I did hear one level more than I heard others though, 105mm, I went with it. Make sure that your plastic tubing will fit down between the spring guide and the tube. Take the tube and make sure that the end you plan to stick in the oil is cut straight. Take that end and measure up 105mm. Put some tape on that mark. When you insert the tube into the fork, insert it all the way to that tape. That way when you suck out the oil to that point you'll be left with exactly 105mm. I found that I had to drain my baster once and reninsert the tube again during the process to get the level down to 105mm.

5. At this point you're done, follow the directions in the manual on putting everything back together.

6. One note when you put the push rod back into the damper rod you displace quite a bit of oil from inside the damper rod. When you are ready to put the push rod in leave the forks completely compressed so that the oil that is displaced will only flow back into the tube and not all over your fingers.

Hope this helps, if I can help further let me know.


[This message has been edited by JJ (edited 06-19-2000).]

Henry, I assume you are talking about the fork cap.

Im not sure what size it is but you definatly dont need an impact wrench. I take mine off with a simple cresent wrench. Although that is not the preferred method, I have White Brothers air bleeders on mine so I cant put a socket on it.

Loosen up your pinch bolts on the UPPER triple clamp. Do not loosen the lower ones yet.

After you loosen the upper ones, put a wrench or socket on it and break it loose. Then loosen your lower pinch bolts and slide your forks out.

If you take the forks out before doing this procedure its not as easy to loosen the cap.

The oil level I set mine at is about 115mm from the top. This might be a little stiff for you but I think the standard level is 125mm.

Good luck!


Darin from Missouri 1999 WR400F

Hey JJ! You beat me on that post. I guess Im going to have to be faster next time! :)


Darin from Missouri 1999 WR400F


Once oil level is set properly, am I right in thinking that after the fork has been fully extended the level cannot accurately be measured? What I've got pictured is that the oil between the inner and outer tube will get forced back into the inner tube once the fork is extended. Seems to me that if you measure after an extension it would show a "false", "higher than I set it" level??? Sound reasonable?

I ran into this scenario when I tried to take a measurement during a fork seal change. Upon disassembly, the oil measurement was 25mm± above what I had recorded setting it from a previous oil change.


Hi guys!

Thank for your advice!! :D

Hey JJ, your steps are indeed very detail,thank alot! :)

And Milkman, you should type faster yeah!

Thank you too!

You guys are really great!!

I will get my fork done soon, thank alot!


Milkman, you are talking about the top fork cap coming off with a wrench, that's correct. What he was referring to using an impact wrench on was the compression valve assy on the bottom of the fork leg.


'99 WR400

'92 GSXR 7/11

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Ken I think I see what you are trying to say. At no time should you fully extend the fork tubes. The fork tube has two holes in the side of them, these allow the oil to disperse into the space between the tubes. What happens if you extend the fork to high is you pull these holes above the oil level and suck air. If you do suck air into this space you will displace just about 30mm of oil for air. That jives perfectly with your experience of having the oil level differ 25mm.

Like I said in the original post to be completely safe you must keep that oil level high, all the way to the top or as close as possible, at all times during bleeding. This will insure that you do not suck any air into the assembly.

You're right Moto I was talking using the impact driver for the base valve not the cap bolt.


[This message has been edited by JJ (edited 06-19-2000).]

JJ or anyone else,

Have you ever modified the shim stack or measured the shim stack of a stock or modified fork? It's easy to do when the compression valve is out and has been disassembled for cleaning. (After the swaging is ground off) Top suspension shops will disassemble and clean the shims of grit from fork internal wear.

Gold Valves are a do-it-yourself stack for your own size and riding style. Has anyone tried them?

Henry, as you can already see the oil level opinion differ...

I weigh about 210, ride mostly trails only alittle MX and ride pretty agressively. My clicker setting to this point had been rebound 10 and compression 9.

Maybe you'll get lucky enough to get more people to post there stats and oil levels and you can make a more educated guess.

Oh, my 99 WR manual states that the stock level is 145mm (European level 125mm). Max is 150mm and min is 80mm.

Yeah! Milkman type faster next time!


[This message has been edited by JJ (edited 06-19-2000).]

Oh yea, your right motogreg. You do need an impact wrench for that. Sorry! :)


Darin from Missouri 1999 WR400F

JJ, Thanks for your help.


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