CBR600F2 fork spring in 1 leg

Started by VFRDom, Jun 08 2012 10:24 PM

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4 replies to this topic

#1 VFRDom

Club Racer

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37 posts

Why VFRD?:Great info here
Location:Ventura County, CA
In My Garage::1998 VFR800

Posted 08 June 2012 - 10:24 PM

I have been thoroughly enjoying my 5th gen for the last few months. The suspension feels a little soft but bearable for my commute. Anyways, going over the maintenance records I saw that the forks had not been serviced in a long time, so I decided to crack them open and take a look. According to the records, the forks were worked on by someone named Dan Kyle who installed a CBR600F2 fork spring in one leg. Only one leg?!

According to racetech's site, the CBR600F2 spring is either .710 or .648 kg/mm depending on the year. If the stock spring rate is .740 kg/mm, what the heck was the point of installing the lighter spring? The CBR spring is also significantly shorter than the stock spring and the oil in that leg appears to be slightly heavier than the other.

Any ideas on why the forks were set up this way?

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#2 Veefer800Canuck

FrankenOwner

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Why VFRD?:I have the V-4 disease and there is no known cure except for copious applications of Throttle!
Location:Whitecourt, Alberta, Canada, Eh?
In My Garage::2010 Honda GL800RR-SP2
Back in business baby!

Posted 08 June 2012 - 10:48 PM

Dan Kyle is a hugely respected superbike tuner.

Putting different springs in the fork legs is a way to split the spring rate. If you have .975 springs and need something a bit heavier, but not enough to use two 1.00 springs, you can custom tailor the spring rate by using one heavier, one lighter.

http://www.kyleusa.com/About_Us.html

We strongly recommend that you use only genuine Honda accessories that have been specifically designed and tested for your motorcycle. We strongly advise you not to remove any original equipment or modify your motorcycle in any way that would change its design or operation. Such changes could seriously impair your motorcycle’s handling, stability and braking, making it unsafe to ride.

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#3 Veefer800Canuck

FrankenOwner

Forum Moderator
11522 posts

Why VFRD?:I have the V-4 disease and there is no known cure except for copious applications of Throttle!
Location:Whitecourt, Alberta, Canada, Eh?
In My Garage::2010 Honda GL800RR-SP2
Back in business baby!

Posted 08 June 2012 - 11:30 PM

So the shorter spring has a longer preload spacer to take up the difference.

Maybe the PO was like a 135 lb beanstalk?

We strongly recommend that you use only genuine Honda accessories that have been specifically designed and tested for your motorcycle. We strongly advise you not to remove any original equipment or modify your motorcycle in any way that would change its design or operation. Such changes could seriously impair your motorcycle’s handling, stability and braking, making it unsafe to ride.

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#4 JZH

International Bodger

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1916 posts

Why VFRD?:I can't remember! Probably something to do with VFRs, though...
Location:Hong Kong SAR, PRC/So. Cal., USA
In My Garage::5 VFRs, an RVF, an ST, a CBR and an RS

Posted 09 June 2012 - 01:01 AM

Interesting. Kind of an Ueber-progressive fork spring unit? (spring-coil bind-spring-coil bind-spring-coil bind-spring?)

(Or, maybe the fork builder was just drunk at the time...) :tongue:

Ciao,

JZH

Hong Kong SAR, PRC/So.Cal., USA
http://www.vsource.org

RS250; CBR400RRN; RVF400RT; VFR400RL; VFR444RN; VFR750FL; VFR800FiY-SC; VFR837FP; ST1300A4 (and counting...)

"After all, what is a motorcycle for if it isn't action?"

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#5 VFRDom

Club Racer

Members
37 posts

Why VFRD?:Great info here
Location:Ventura County, CA
In My Garage::1998 VFR800

Posted 09 June 2012 - 09:06 AM

I'm the third owner of the bike and the fork work was done by the original owner. The PO told me the bike was set up for a 200 lb rider and I believed him, oh well.

For now I'll just change the fork oil until I decide on what spring rate to use. Time to do some searching on VFRD.

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