Hyperpro linear springs: what mm oil level does their 500 cc actually give?

[mr.millman]

Fork oil level with Hyperpro linear springs on an ST1300, anyone done this?

2003 ST1300A, 122k km. Fitting Hyperpro linear 9.5 N/mm springs (kit SL-HO13-SSA002) next week along with seals, dust covers and bushings.

Hyperpro's label says SAE 7.5 and 500 cc. Honda specs 638 cc and a 62 mm level with the stock spring. Their own instructions tell you to set a level in mm, but the label gives a volume, so there is no mm figure for this bike. I have asked Hyperpro and I am waiting for an answer.

What I have found here is that most people run 120 to 130 mm with aftermarket springs, since the high stock level is there to compensate for soft stock springs. One member said a single liter of Hyperpro fluid was just about right for both legs with Race Tech springs, which lines up with 500 per leg.

So, if you are running Hyperpro linear springs:

What mm level did 500 cc actually give you in a fully drained leg?
Did you stay at their figure or go your own way?

The springs measure 250 mm free length, same as the Honda spec of 249.6, so the stock spacer stays and preload is unchanged. I am planning on 550 cc measured out, then I will note the level in mm and keep that as my reference.

 

[dduelin]

Calculate the height of a cylinder with a volume of what ever volume in cc cubed you desire. You will need the ID of the fork tubes and the volume in cc to calculate.

Right cylinder
Solve for
volume




V
=
π

r
2

h

r Radius h Height

The volume of a cylinder is calculated using the formula V = π r² h, as explained by the Volume of a Cylinder Calculator.


Formula Components

• • V: Volume (cubic units like cm³ or m³)
  • π: Pi, approximately 3.14159
  • r: Radius of the circular base
  • h: Height (or length) of the cylinder
    AxFlow +2
    

How to Calculate

1. • Square the radius (r × r).
   • Multiply that result by Pi (π) to get the area of the circular base
     .
   • Multiply by the height (h) of the cylinder.
     YouTube·Math with Mr. J +1
     

Note: If you only know the diameter (d) instead of the radius, divide the diameter by 2 first (r = d / 2).
CK-12 Foundation


If you have specific measurements, tell me the radius (or diameter) and height, and I can help you calculate the exact volume.

 

[Larry Fine]

Don't you need to compensate for (subtract) the volume of the spring and other components?

 

[Igofar]

I ran 120mm oil height, and a 130mm spacer, with 7 weight oil.

 

[Larry Fine]

It's good to see you again, Larry.

 

[TerryS]

Calculate the height of a cylinder with a volume of what ever volume in cc cubed you desire. You will need the ID of the fork tubes and the volume in cc to calculate.

Right cylinder
Solve for
volume




V
=
π

r
2

h

r Radius h Height

The volume of a cylinder is calculated using the formula V = π r² h, as explained by the Volume of a Cylinder Calculator.


Formula Components

• • V: Volume (cubic units like cm³ or m³)
  • π: Pi, approximately 3.14159
  • r: Radius of the circular base
  • h: Height (or length) of the cylinder
    AxFlow +2

How to Calculate

1. • Square the radius (r × r).
   • Multiply that result by Pi (π) to get the area of the circular base
     .
   • Multiply by the height (h) of the cylinder.
     YouTube·Math with Mr. J +1

Note: If you only know the diameter (d) instead of the radius, divide the diameter by 2 first (r = d / 2).
CK-12 Foundation


If you have specific measurements, tell me the radius (or diameter) and height, and I can help you calculate the exact volume.

Not so fast there chief...the fork leg that you are filling also contains the damper cartridge: the tube, the base, the shims and valves and the damper rod. So you'd want to factor those into the volume as well. But I agree that you do not need to consider the spring as that is added after setting the oil height. I agree that for oil height, 130mm is about right with linear springs (and is what RaceTech recommended to me).