Gs1000G forks servicing

[Lorenzo]

The forks are not air assisted, but they seem original (37mm OD, all the mounting holes in the right position) the spring is a progressively wound one, 470mm length by 26mm OD;
There appear not to be a spacer, only a 20mm alu block with one hardwearing surface, just below the four position preload knob, which has an ovelall lenght of 60mm.
Later on, when I'll take the second fork apart, I will post the length of the piston, along with the relevant pictures.

My question is, how to go about oil level?

The springs might be Wirth or Progressive and in the latter case, their tech literature states to follow the manual prescriptions, in this case 251ml and in any case not to go above the 140mm from the brim of the fully compressed inner tube.

Where does it leaves me?

Thanks

[Nessism]

What's wrong with "140mm from the brim of the fully compressed inner tube"? FYI, you need to remove the springs before measuring.

[Lorenzo]

Yes I know, but the Progressive people, recommend to stick with the Suzuki setting, so 251ml of oil (which is way below the 140mm mark) and not to go more than 140mm.
Now, the GS springs should be no less than 416mm while the one I got are 470, plus, according to Progressive again, their springs displace more oil, so if is true their first statements, to follow whatever the manual prescribe, I should be OK either with 251ml or an amount of oil wich is greater than that I.E. 140mm from top(defenetely more than 251ml).
Am I talking nonsense or there is a paradox?
Thanks

[RichDesmond]

What is the level with 251mm? I would think that 160mm or so should be good with the Progressive springs.

[Lorenzo]

Did not measure, I will when I open the second fork;
Please read the #3 post

http://www.progressivesuspension.com/pdfs/forksprings/3055.pdf

Second paragraph

Thanks

[Nessism]

Anywhere from 160 to 140 is fine. Doesn't matter. As long as the damper rods are submerged the damping will be there. It's not like there is more damping just because you add more oil. The thing with the height is they are trying to manage the trapped air column size. In theory the more oil the higher the trapped air pocket pressure will be at full compression. In the real world the difference between 160 and 140 doesn't matter. I've got the oil height at the max recommended level from Progressive and the forks are not overly harsh, even when bottoming. This is one of those instances where splitting hairs on the spec isn't necessary.

[RichDesmond]

Anywhere from 160 to 140 is fine. Doesn't matter. As long as the damper rods are submerged the damping will be there. It's not like there is more damping just because you add more oil. The thing with the height is they are trying to manage the trapped air column size. In theory the more oil the higher the trapped air pocket pressure will be at full compression. In the real world the difference between 160 and 140 doesn't matter. I've got the oil height at the max recommended level from Progressive and the forks are not overly harsh, even when bottoming. This is one of those instances where splitting hairs on the spec isn't necessary.

Exactly. I would run it a little lower personally, (160ish) but it's not a big deal either way.

[Lorenzo]

OK thanks to both of you.
The ride was harsh, so it can only get better.
Reading stuff, comes out that even a 20mm differwnce would matter...
Frankly all I was trying to gather was, how much leeway I got before the forks would go into hydrolock.

As I said, having read stuf about suspension, I came to the conclusion that linear springs, possibly along with cartridge emulators are really the best option for our bikes.
That's the way I will go, if I cannot breathe some life into them forks.
Thanks

[Steve]

The forks are not air assisted, but they seem original (37mm OD, all the mounting holes in the right position) the spring is a progressively wound one, 470mm length by 26mm OD;

The springs might be Wirth or Progressive ...

They could also be stock springs. I have not noticed exactly which models but some models had progressively-wound springs and others had two separate straight-wound springs.

I agree with the lower oil level (higher number number), it gives a lower progression in spring rate as the forks are compressed.

.

[Nessism]

What weight of oil are you using? In my experience 15W is on the thicker side of normal for GS forks. Straight 15W in cold weather can lead to a little harsher ride than 10W. Overall though, the GS suspension is pretty darn nice, doubly so when you consider the age of the bikes. Suzuki certainly did us well regarding suspension, soft fork springs excepted.

[Lorenzo]

Actually 15W, I had two 500ml cans lying around, I know 10W would have been better.
Lets see how they perform.

[Lorenzo]

What is the level with 251mm? I would think that 160mm or so should be good with the Progressive springs.

251ml equals 140mm

Apparently there is a model coded E (European)? that fits with the specs of my bike, I.E. no air assistance and longer springs without a spacer.
Tanks

[RichDesmond]

251ml equals 140mm

Apparently there is a model coded E (European)? that fits with the specs of my bike, I.E. no air assistance and longer springs without a spacer.
Tanks

Higher than I would have guessed for such a small amount of oil. I always forget how little oil the older, skinny fork tubes take.