Airgap with Hyperpro front springs

[Donatello]

Hi so my Hyperpro front springs came in yesterday and I noticed there was only 1 liter of oil included (SAE 20) and the manual recommends an oil level (same as airgap?) of 240mm!
The normal airgap is 108mm on normal springs so I am surprised Hyperpro uses a lot more of a gap with their springs. Is this normal?

[gsxbarmy]

It's not abnormal with aftermarket springs for the air gap to differ. Hagon have their own air gap, the Ohlins I had in mine were different, so yes it's to be expected.

How they compensate / offset this is by changing the oil SAE - I see on your spec sheet that they recommend SAE20 - standard is SAE 5, so they are using a heavier weight oil which compensates for the less oil (basically meaning the springs do more work).

Set it up with the oil/air gap they suggest, using the weight fork oil they suggest and the settings they suggest and all will be good. You just need to tweak your standard fork settings afterwards for how you like the forks to operate.

Just for the record, this is how it varies with other manufacturers:

Fork oil:
-  5W Fork oil recommended with  standard springs
-   10W Fork oil typically used with aftermarket progressive / linear springs

Oil/Air Gap:
-   Standard springs: 108mm
-   Hagon progressive: K2-K4: 150mm,  K5-K8: 160mm
-   Ohlins progessive: K5-K8: 140mm

[Donatello]

Yep I saw the airgap other companies use but Hyperpro is a bit extreme if you compare them on paper. I'll use their setting, I used Hyperpro on previous bikes and was always satisfied with their products for sporty riding on the street.

[KoZi]

I did this setup. Every thing exactly as they say. After this mod You have to change preload and rebound/compression to have a properly SAG

[Mister Fishfinger]

It's not abnormal with aftermarket springs for the air gap to differ. Hagon have their own air gap, the Ohlins I had in mine were different, so yes it's to be expected.

How they compensate / offset this is by changing the oil SAE - I see on your spec sheet that they recommend SAE20 - standard is SAE 5, so they are using a heavier weight oil which compensates for the less oil (basically meaning the springs do more work).

Set it up with the oil/air gap they suggest, using the weight fork oil they suggest and the settings they suggest and all will be good. You just need to tweak your standard fork settings afterwards for how you like the forks to operate.

Just for the record, this is how it varies with other manufacturers:

Fork oil:
-  5W Fork oil recommended with  standard springs
-   10W Fork oil typically used with aftermarket progressive / linear springs

Oil/Air Gap:
-   Standard springs: 108mm
-   Hagon progressive: K2-K4: 150mm,  K5-K8: 160mm
-   Ohlins progessive: K5-K8: 140mm

Yes but there is no agreed standard for fork oil viscosity. Brand A's 5W might be nothing like brand B's 5W. I didn't realise this until I read Andre's excellent post on the subject:

http://gsx1400owners.org/forum/index.php?topic=3091.msg39369#msg39369

This is no problem if you are using the oil that Hyperpro supplied (because you would assume they know what they are doing), but worth bearing in mind if you switch to a different brand when doing your testing.

[grog]

I dont have Hyperpro in forks but do have Wilbers. Made huge difference. Most settings , pre load etc , had to wind way back. 2 most noticed things were , very compliant over bumps,2nd was no more dive, under brakes or between gears, way better. Transformed my bike really, took a while to realise it was same bike. Hypers im sure will be as good. Let us know.

[Jonah1400]

Hi all .been looking at this post as have hyperpro springs in mine and due for oil change ( shop did it originally) but doing it myself this time .
Question though .
How much oil do I need ? Generally I mean is a 1 ltr enough for both forks ?
Cheers
Safe riding .

[Andre]

Hi Jonah, it is customary to introduce yourself here https://gsx1400owners.org/forum/index.php?board=20.0

1 liter should be enough as the air gap (oil level) that Hyperpro specifies is 240 mm according to the doc shown in post #1. That is more than double of that of K2-5 (108 mm) which requires 644 ml each. 10 mm gap difference equals 15 ml oil. That calculates to 446 ml for each fork leg.

If you just pour out the old oil, you won't need the whole 446 ml. However, I advise to do a thorough job (as per service manual) as a lot of sludge (the stuff that holds most of the metal particles) won't come out by just pouring.

[gsxbarmy]

Hi Jonah, it is customary to introduce yourself here https://gsx1400owners.org/forum/index.php?board=20.0

1 liter should be enough as the air gap (oil level) that Hyperpro specifies is 240 mm according to the doc shown in post #1. That is more than double of that of K2-5 (108 mm) which requires 644 ml each. 10 mm gap difference equals 15 ml oil. That calculates to 446 ml for each fork leg.

If you just pour out the old oil, you won't need the whole 446 ml. However, I advise to do a thorough job (as per service manual) as a lot of sludge (the stuff that holds most of the metal particles) won't come out by just pouring.

I see also that with that oil/air gap that Hyperpro specify SAE20 weight fork oil

[Bri1100]

About to fit Hyperpros soon, think I read somewhere on here I should ditch the large white spacer would that be correct? Can't go down to garage to check old spring length with new one as it's bloody freezing 😬

[seth]

@Bri1100
I'd follow hyperpro's instructions fully.
If you don't have the instruction then I would contact them or check thier website for details .
Good luck