Fork oil

[porter]

Hi. Removed my veeks forks today to change the oil. With springs and spacers removed and fork  compressed the manual says the air gap should be 120mm. My left fork was at 70mm and the right at 100mm. Not sure what grade the oe oil is, only a part number Iin the manual.  I'll put 5w in. Springs are progressive but no weight marked on them.  Not sure if I'll replace these.
I've been happy enough with the springs it was just the high speed compression (ie small sharp bumps) I didn't like.

[porter]

Ps. Anyone used hyperpro fork springs in this model? If so what's your thoughts.  Ta.

[joethebike]

Something that worked for me in trying to improve small bump compliance on my 650 forks was to reduce the oil level by 50ml in both legs which has the effect of reducing the compressing air spring effect as they work over a bump. I use ATF in the forks.

[greywolf]

Small, sharp bumps are always going to cause a problem. Those are the ones that stiction and inertia are going to magnify. I like a minimal compression damping setting to help with that on bikes with separately adjustable compression and rebound damping, whether by setting an adjuster or changing valving. It's not about the spring rate at all if big bumps are not bottoming the forks. I'd rather go for a stronger spring than more compression damping if the forks bottom. Motorcycles have a lot more unsprung weight compared to total weight than cars do.

[Hondaman]

Interesting that you mention stiction, my stock glee forks have lots of stiction as soon as you fit the (oe) fork seals, lots more than the 1k forks & whatever seals they had in.

It would be interesting to go the extra mile to try the low stiction skf seals as a comparison.

[porter]

Been searching online but its a mixed bag of info. Wilbers web site say 5w oil with a 135mm air gap and their springs yet hyperpro say 10w with 120mm air gap with theirs. I think  the wilbers  set up sounds better.
This worked on my last bike, a triumph tiger800 road which have very harsh forks as standard.  A change to 5w oil and a 150mm air gap helped that bike a lot.

[Simmo24]

Hi

From the manual the oil used is :-

Fork oil  99000–99044–L01 (Suzuki FORK OIL L-01)

From Googling :-

0W grade, 1L:99000-99044-L01
5W grade, 0,5L:99000-99044-05G
10W grade, 1L:99000-99044-10G
15W grade, 1L:99000-99044-15G

Here's a viscosity chart

http://www.mediaturbo.com/clients/marzocchi/forkoilviscosity.html

From this it would seem that labeled weights are meaningless.

[Hondaman]

Fork oil level only acts as a kind of spring assister as the forks compress, giving the forks a progressive action, even with straight rate springs.
This is further complicated by some (progressive) spring suppliers wanting the tighter wound part of the spring down, othere wanting the tighter wound part upwards - this will have an effect on oil level with the spring installed.
It could be one manufacturer has a softer spring & the extra oil height helps bottoming, it could be their testers deem a firmer ride.

Who knows which is best, it's pot luck without extensive side by side testing.

As above fork oil viscosity is another variable to muddy things, best choosing by cst

[porter]

The oil I took out looks like 5w. I have some 10w and 2.5w in garage, looks thicker than one and thiner than other.
I can only find wilbers r hyperpro spring for the Veek at the minute,  hagon will have one in a month r so.
But as greywolf says I never bottom out on brakes r bump even two up so springs not to bad really, just when it's all apart it would be easier to replace.
Its impossible to compare two different bikes but I put hyperpro springs in a tiger 1050 before and they where not the best so hesitate to buy again.

[porter]

Finally got the forks back together.  Put hagon springs in, much firmer to compress when fitting and they have a smaller progressive section (40mm) than the oe springs (60mm). Air gap is 135mm with 5w oil,  oe is 110mm.
Stll feels the same though.  When you compress the fork legs by hand the right one is firmer than the left but with the hagon springs and large air gap the right is still much firmer than the left. I'm a bit stumped,  stripped forks down again but all was fitted OK.

[Simmo24]

I softened the compression damping by a click on mine and that helped a lot with the vibration over ripples and sharp bumps in the road surface.

[porter]

I tried all that on mine too but was never happy with the harsh front end, specially after switching to Bridgestone a40's. Thought I'd found the problem when I found the fork oil levels where wrong, 100mm in left 70mm in right but maybe not. I've removed the springs again, check oil level (now 135mm) and spring installation,  all OK but still the right fork is firmer to compress by hand than the left, all adjustments equal.  Hopefully salt will be away of the roads soon and I'll get to try it out.

[porter]

Had my first run out yesterday with new springs fitted. Bike sitting much taller at front, less sag and much firmer and more support on the brakes etc, as you'd expect with a heavier spring. But damping still much the same, not quite as harsh with lighter oil but its still there. I'll play about with the adjustments over the next few rides.
So is this worth doing? If your carrying heavy loads then yes as springs are better but if your doing this to try to fix the harsh damping then no, you need a re valve. 
Ps. fitted ebc double h rear pads, big improvement.