how much oil to add (forks)

Question for you suspension guys. My forks are working great, I finally got them dialed in perfectly for most stuff. However lately I've started to bottom them at least once a lap, and once every couple of laps when I overshoot a tabletop or something I get a really harsh clank kinda bottom (ouch!). I want to add some oil but I'm not sure how much. I'm 160# w/o gear and the oil is currently at 130mm. Is 15mm enough to make a significant difference?


I added 15 mm to mine (to 115 mm) and it made a HUGE difference for me. Took away that harsh bottoming. Went out 2-3 clicks softer as well!

I am 185 lbs w/o gear though. You might try adding just 10 mm to begin with. It may be enough for you.


Steve T

In fear for my life, I run it at 90mm.

When it comes to casing, I need all the protection I can get.

Don't be afraid to experiment. It's an easy adjustment.



I've been raising my oil level a little at a time to get the right feeling.

I just add oil by the bleeder screws, 5cc to each side, then go on the track to overjump a few obstacles, if that's not enough, I add some more!

After you should check that you didn't went too high, that would mean that you need stiffer springs or valving.

5cc should be a little less than 10mm.

When your mid-valves starts to get tired you should have to raise the level some too.

Just my .02$ (canadian $ = not


I put new fork seals on my bike last night. I wanted to know how much oil it would take to raise the level 5mm. Using a medical syringe I determined that approximately 35cc of oil will raise the level 5mm. this is with the damper rod, and spring guide in place (no springs). Now if I want to stiffen it up a little I can just add the 35cc and know I raised the level 5mm.


You measured something wrong somewhere along the line. There is no way 35ccs of oil is only 5mm in oil level change. Adding 35ccs of oil to a fork tube is a gigantic change!


I screwed up, make that 3.5cc. I added a zero where there was none. Thanks for pointing that out. 3.5cc is the volume of oil needed to go from 120mm to 115mm in height. That volume could change depending on where the oil level is on the damper rod and spring guide.

Going to the 115mm height and running 14 clicks out on the compression was a huge improvement for me.


I've got stock setup. When adding fork oil, is it okay to add a different brand of oil? I assume I must stay with the same weight. Does anyone know what weight comes stock? I don't have the manual with me and I wanted to pick some oil up on the way home.

Thanks for the help!

I use 5wt Bel-Ray. I believe 5wt is stock and I don't see any reason why you couldn't mix brands, you would only be adding a small amount.


I think KYB 01 is a 3wt - but I'm not totally sure.

And I ran out of the KYB stuff the other day (it's been on back order for the last month) so I switched to a special Bel Ray racing fluid that I think only comes in 3wt.

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