Front Fork Maintenance Help



5 replies to this topic
  • rss

Posted December 04, 2000 - 05:02 PM

#1

I am looking for some help regarding the changing of the front fork oil on my 2000 WR.
I have about 375 total miles on my bike and have never changed the fork oil, so my questions are:
1. How often (in miles) should I change the oil? The manual says after break-in, then every 1000km.(620 miles).
2. Can the oil be changed without removing the forks from the bike as the manual says?
3. The manual says the oil capacity is 19.4 US oz. Is that per fork leg or for both?
4. Is there any truth to the bleeding of air from the forks before each ride?
5. Does anyone have a simplified procedure to change the fork oil?

  • Mark_M

Posted December 04, 2000 - 05:30 PM

#2

Good questions, I had some of the same questions...

  • MS

Posted December 04, 2000 - 06:24 PM

#3

Guys:

Here is my 2 cents worth on that topic. I currently ride a 98 WR, so Im not sure if Yamaha still uses Kayaba, but Im pretty sure they do..

I want everyone to correct me if Im wrong, because I know there is several ways to skin a cat, figure of speech of course.

Here goes.. yes you do have to remove the forks from the bike to change oil.

If you are able and willing to do this, please read on...

1. place bike on race stand or suitable stand
2. remove front wheel
3. remove brake caliper
4. loosen lower triple clamp bolts
4. I think that the top fork bolt is about 17-19 mm. this is my method, so others will be different.
5. I loosen top triple clamp bolts and slide each leg out individually.
6. I have an air gun, and I hold the forks in my hand standing straight up and give it a quick shot of air on the top cap bolt.

Here is where the fun starts, when you get the top fork bolt off, or top cap, whatever, it is attached to the dampner rod assembly, at this point the upper fork leg will lower itself and you can drain the oil out into your favorite pan.

Now, to get the new oil in.. you must remove the fork spring. I think the dampner rod assembly has a 14 or 17 mm nut, you must lower the spring by hand, while holding the spring down, you must insert the wrench onto this nut, now hold it and then take off the top fork cap. Once the cap comes off, the dampner rod will sink back into the fork and you can remove the spring.

Don't concern yourself about the amount of oil in the fork based on CC's or oz's. Look at what type of riding you do and decide if you want the fork stiffer or softer. a Softer ride, you want lower fork oil, a stiffer ride you want higher fork oil. By this I mean the fork oil distance from the top of the fork tube.

Your manual (service at least) will give you minimum and maximum fork oil height levels, my 98 manual calls for a height of 40-150 I think, I currently am using a height of 145mm, what this means is, is that the fork oil level is 145mm from the top of the fork tube.

after you get to this point. You can add your oil, with the forks compressed and spring out and dampner rod out. Go ahead and fill that sucker up to the top with your favorite oil, I use Honda SS7 5w, now, take your fingers and grap hold of the damper assembly and lift slowly up to the top of its stroke, and go back down. Do this about 10-12 times, slowly, this is called bleeding the air out. Once you have done this step, now it is time to set your height of the oil in the fork.

Remember, the greater distance of oil from the top of the tube, the softer and more plush, (hence, easier to bottom out on big hits) the closer to the top, you will get a more stiff ride with less bottoming.

The easiest way I have found to suck the oil out to get to your desired level ( without involving your significant other) is to use a brake bleeder tool. YOu know, the plastic looking pump hand tool, about $40 bucks at Sears I think, anyway, measure your desired height in mm on the tube you stick in the forks, take a piece of tape, electrical or something with color and mark your lenght you measured on the tube. Now insert the tube into to the fork and stop the tube at your measured tape part at the top of the fork tube. Now start sucking oil into a bottle, jug or pan, when your bleeder tool stops sucking oil andyou start getting air bubbles in your dip stick tube, you have just set your fork oil height.

Now, you have to do this again for the other leg!!! sounds like fun doesn't it???

after you set your height, you must grab hold of the dampner assembly and lift to the top of the stroke, hold momentarily, then let it go and slide your spring on then grap your assembly before it goes back down into the fork tube. insert the dampner rod and attach your top fork cap, you must and I repeat, you must secure the top fork cap securely to the dampner rod assembly, ala, hold the spring down, and reinsert your wrench and tighten the nut. Now bring the fork tube back up to meet the fork cap and thread back into the fork, do not < I repeat, do not cross thread this, they are very fine threads, make absolutely sure you do not cross thread this, and retighten,

now your are ready to do the other leg aren't you?? after doing this, I then push down on the fork legs myself to feel the compression and to see if the forks move freely and to circulat the oil.

Or, you can dismount the forks from the bike and take to your local shop and have them change the oil for you, just specify the fork oil height you want and they will set it for you , and you can pick up next day.

I hope this answered your questions.

MS

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  • fershy

Posted December 04, 2000 - 06:29 PM

#4

Originally posted by rss:
I am looking for some help regarding the changing of the front fork oil on my 2000 WR.
I have about 375 total miles on my bike and have never changed the fork oil, so my questions are:
1. How often (in miles) should I change the oil? The manual says after break-in, then every 1000km.(620 miles).
It is imperative you change the oil almost immediately after break in. Especially with the 2000's as they have aluminum sliders.
You oil will be contaminated with aluminum particles which accelerate wear on the internals. After the initial break in service intervals can be surely go 1000km as per the manual, perhaps more depending on your riding conditions. Chances are you will blow a fork seal by the time you figure it is in need of a change.
2. Can the oil be changed without removing the forks from the bike as the manual says?
Yes. Buy an extra bottle of fork oil to use for flushing. Pump the forks with springs removed to drain all the fluids. Repeat until you are confident that all the particles are flushed from the fork.
3. The manual says the oil capacity is 19.4 US oz. Is that per fork leg or for both?
Don't worry too much about this spec. You will want to measure the oil level to the top of the fork (springs removed) Manual recommends 80-140mm. 100-110mm is ball park I recommend Golden Spectro 5 weight. If memory serves you will need 4 bottles to get the job done. One more if you want to ensure a real thorough flush.

4. Is there any truth to the bleeding of air from the forks before each ride?
Yeah not a bad procedure to add to your checklist.
5. Does anyone have a simplified procedure to change the fork oil?

You got it!

fershy

  • Scott_F

Posted December 04, 2000 - 09:25 PM

#5

Regarding the MS post:

4. Loosen the top clamp bolts first, then the fork caps, then the lower clamp bolts. Reverse for reassembly.

The oil change method described by MS is the bare minimum procedure, and it leaves a fair amount of old oil and contaminants in the fork. A thorough oil change requires complete disassembly and cleaning of the fork. This is even more important with new forks which have a lot of metallic debris. If this is beyond your experience, then it would be wise to find a suspension tech who can do it for a reasonable fee. Try to watch the procedure so that you can later learn to do it yourself.

  • rss

Posted December 05, 2000 - 03:49 PM

#6

Thanks for all of your responses.




 
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