Hyperpro progressive springs - air gap & fork oil?

Hi all,

Installed them springs on me K3 naked pointy some years ago. Now I wanna change forkoil, but lost original doc. Is there somebody who still knows what air-gap height above forkoil should be? No response from Hyperpro labs. Is there a lot of difference between Hyperpro 15w forkoil and other label sae15 forkoil?

Thnks.

[yorkie_chris]

I was asking them this, helpfully they won't tell you the cSt rating of their oil or the VI. Obviously they don't consider Joe public qualified to look at numbers more complicated than multiples of 5.

There ya go. Credit to Peter Verdone where it's due. As you can see the SAE viscosity has little bearing on the behaviour of the oil.

Impressive & interesting list Yorkie. If I would know the operating temp. of forkoil in my sv during summertime I'd have an indication of which cstks column to use to have an idea of viscosity and thus dampening properties of the fork with that oil.
No clue to where the Hyperpro 15w would fit in though. As you say, the sae "15" indication doesn't say a lot.

From the Hyperpro progressive spring mounting manual:-

sv650 / S year: 03>

hyperpro oil: sae 15
oil level: 140mm
spring preload: pos 4-5
static sag: 22mm

I had this for a while but it didn't solve all the problems you get - changed to Racetech cartridge emulators, linear springs (0.91) 15W oil (decent stuff, the hyperpro oil went sludgy in 12 months) and Traxxion damper rods. Much better - if you have the cash.

Thanks Rich, 140 mm air chamber check. Yes quality of Hyperpro oil is not that good I think, my fork became fuzzy after 1 year too. What oil (label) did you put in?

Not sure - think it was a silkolene - had it done at Reactive suspension in York - so I didn't actually buy the oil.

Just remeber that we were both very surprised by the colour/quality of the oil after such a short time - especially in one of the forks (strangely).

[yorkie_chris]

Silkolene make 2, they make fork oil and pro RSF. The pro RSF is what penske use in their shocks and is fully synthetic.

If oil is black after a short time, are you sure you cleaned them properly when you put it in?

[yorkie_chris]

Originally Posted by philbond07

Impressive & interesting list Yorkie. If I would know the operating temp. of forkoil in my sv during summertime I'd have an indication of which cstks column to use to have an idea of viscosity and thus dampening properties of the fork with that oil.
No clue to where the Hyperpro 15w would fit in though. As you say, the sae "15" indication doesn't say a lot.

I don't think fork oil runs that hot as the fork is a huge heat sink right in the air blast.

If anyone fancies putting a temperature sensor inside their fork that would be ace!

Silkolene fork oil 15w has a quite low VI in Yorkie's list. The Bel-ray just next in the list keeps higher viscosity at higher temp. Silkolene Pro also looks much better. Hmmm. Anyway I think the Hyperpro oil is not so very special. I guess I'll just study the list and take one of the better specd oil out of there.

Thnks a lot for all the help gentlemen.

Ok now FWIW: I bought a can of Denicol "SAE15" forkfluid with advertized viscosity of 46 cst@40°C. But when I took the Hyperpro 15w out of the forks, it was visibly immediately clear that it was way thicker than the Denicol oil. This only means the 15W Hyperpro is more than 46 cst.

I decided not to put the Denicol oil in, but instead I'm going now for a can of Motorex or Elf 15w fork oil, both about 70 cst.