[CessnaA&P]

Anyone know what the stock spring rate is for the OEM forks on a 2005 F4 1000s?
And at the same time the rates for a 2007 1078 R312 Euro model OEM fork?

Trying to figure out why my bike has a lower ride height after the front end swap to the 1078 R312 front end everything was set to what the manual calls for I’m thinking the lower sliders are shorter from what I came up with looking at the workshop manual the 1000s has a travel of 133mm with the 1078 having a travel of 129mm.

I have a 2005 F4 1000s

 

[silentservice703]

We went down this road several years ago and the short answer is no. No one knows the spring rates.

 

[CessnaA&P]

Cool works for me. Thank you Sir

 

[silentservice703]

Marzocchi springs, on the first generation bikes anyway, have a unique shape. When I uprated the springs on my 2007 312R, I first used Ohlins Springs. The straight coils of the Ohlins units "bumped" an internal follower and felt awkward. I then had Marzocchi supply a recommended spring rate and that solved all issues.

You can see the shape here (Stock spring is on the bottom or right):



...and the change in wire diameter here:

 

[CessnaA&P]

I see I might just try and swap out the 05 fork springs to the 07 1078 R312 forks and see what's going on from there. It might just be they went to a softer spring on the newer forks with the bigger Cartridge, If I'm not mistaken the 05's have a 16mm Cartridge and the 07 1078 R312 have a 26mm Cartridge. But then I'm just guessing

 

[theknurl]

?

Just measure the spring rate >
Put a digital scale on a drill press, put a bolt with a large washer in the chuck
Put the spring in a PVC pipe, slide the spring over the end of the bolt
Lift the PVC pipe off the scale
Lower the quill to an even inch mark, push the tare button
Lower the quill one inch, the scale shows the spring rate

It's called Hook's Law
:grin2:

 

[number2]

Noel you are the man

 

[silentservice703]

@CessnaA&P: FWIW, there is no such animal as the '07 1078 312R.

The '07 and early '08 F4 was a 998 cc engine and designated the 312R.

The latter half of '08 and all of '09 the displacement was 1078 cc and the bike designator changed to F4 1078 312RR.