Replacing Fork Springs~ Which Fork Oil to Use Now?

12 replies to this topic
  • basicblues

Posted August 27, 2003 - 10:11 PM


I am stepping up to heavier fork springs this weekend. I am going to change my fork oil and wanted to know what everyone here on TT uses. Recommended oil weight and oil level or amount (oz./cc.)? Thanks

  • Sean_McCutcheon

Posted August 28, 2003 - 06:29 AM


I just put 10 wt in my forks and love it on the track. I haven't got a chance to ride it in the woods yet. I think the amount to add to the forks was 572 cc's.

  • basicblues

Posted August 30, 2003 - 06:33 AM


I am heading the shop today to purchase fork oil. I didn't get much input here so I post again as to what I wind up using. :)

  • MN_Kevin

Posted August 30, 2003 - 01:49 PM


the best way to do this is to use the "SEARCH" feature at the top of this page, WR400 forum, keyword "fork oil".

We have in the past gone over this extensively.

Also try the YZF450 forum as well.

  • basicblues

Posted September 01, 2003 - 02:50 PM


I've done a search on this topic, while this topic may have been gone over extensively, it still lacks accurate information and opinions seems to vary. Several threads end up discussing something other than the original post.

I went to my local dealer yesterday and talked with the service manager/head mechanic and he recommended using 20wt fork oil (BelRay I presume). I don't remember seeing a thread that mentioned using 20wt fork oil. Seems a little on the heavy side to me since most are using 5-7wt oils. He also claimed the stock oil was 10wt. I don't think the service manual states actual oil weight other than recommending the use of suspension oil "01". What is the true weight of "01" fork oil?

I am bumping up to 48 fork springs and thought I would inquire about fork oil brands, fork oil heights or fluid level cc's and accurate fork oil weights. Stay with stock fork oil and increase oil height? Stay with stock height and increase oil weight? Complete tear down necessary to remove all stock oil (as previously posted) or would a simple drain and refill be adequate? etc...etc...

  • cnacc

Posted September 01, 2003 - 03:10 PM


20 Wt??????? :) some one has been in the crack!

It all depends on what you weigh and how you want it to preform. The thicker the weight oil the slower things will happen. What I mean is think or it like pushing veg oil or Syrup through a syrenge. the oil will move much quicker than the Syrup. You will want the one that will give you the best end result. To heavy and the fork will feel really slugish and harsh.
If you are putting 48's in you are either big or going big. If you are bottoming out then increase the oil hight, but you don't need to go heavier on the oil. Proper spring preload is also important for proper set up.

Presonally I would run 7.5-10 wt and think about increasing the oil height.

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  • Indy_WR450

Posted September 01, 2003 - 06:46 PM


I like 10wt at 105 mm from the full level. But I am on the heavy side of the riding scale. :)

  • cnacc

Posted September 02, 2003 - 09:51 AM


Yeah I am definitely in the Clydesdale class, 240. When I installed my .48 I went to 10Wt oil and 90 mm from full.

  • basicblues

Posted September 02, 2003 - 03:52 PM


What brand of 10wt fork oil did you use?

  • MN_Kevin

Posted September 03, 2003 - 03:03 AM


it still lacks accurate information and opinions seems to vary

You will find as many opinions on fork oil as engine oil.

The rule of thumb, in this case (which REALLY should be a surprise - for once) is the more expensive the oil, the better it is.

The reputational rebuild shops use either Spectro, Pro Circuit, Showa, KYB 01, Race Tech or some derivation of each. Many have SWORN the KYB 01 gave the most supple performance (don't read this as BOTTOMING).

And KYB is at the top of the heap $$$ wise.

I personally wouldn't use the conventional oils in my conventional forks (Honda CB750 Nighthawk w/ Race Tech's Cartridge Emulators, or my little 2003 TTR 125LE)

Also, I do BELIEVE and DO CORRECT me if I am wrong, is the KYB and Showa SS is 5#...I think.

In either MXA or Dirt Rider a while ago, they talked of oil. That is where I recall "if my memory serves me right (Judge!)" it said it was, the KYB amd Showa SS was 5#.

BTW, there ARE two grades of Showa SS. THe other is 7# I believe.

If you are respringing w/ NO REVALVE, you will more than likely need heavier oil.

  • dominator426

Posted September 03, 2003 - 02:08 PM


Amsoil makes excellent synthetic <font color="black"> Shock Therapy Suspension Fuid in 5 and 10 weight for $8.75(USA) a quart. It works great on mine... Better protection and highly stable under temperature variations.

  • basicblues

Posted September 03, 2003 - 05:58 PM


Thanks guys, this is the kind of information I was looking for... :)

  • cnacc

Posted September 04, 2003 - 06:47 AM


I have used Belray, and Race Tech. Both seemed to work gust fine. I think the big thing is to change it about every 6 months W/normal use.


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