fork spring questions

[Racing Geek]

I'm looking for the fork spring rate, outside diameter, and length for a...

 

88 gsxf 1100:

.468 kg/mm is what my searching has turned up

?? OD

?? length

 

86-88 gsxr 1100:

?? spring rate

?? OD

?? length

 

85-87 gsxr 750:

.58 kg/mm is what my searching has turned up

?? OD

?? length

 

Plan is to respring my mini moto on the cheap and some searching I've done shows the above bikes might have the right size fork springs to keep my fat ass from bottoming out the little bike. Hoping someone here could confirm some dimensions for me.

[dupersunc]

Hours of fun here.

http://www.racetech.com/VehicleSearch#genre=2&brand=&model=&year

[Racing Geek]

That's where I got the stock spring rates from but it doesn't give the stock lengths or stock diameters.

[Oilyspanner]

The width in mm and length in cm are normally given eg on GSXR1100 86-88 page it has  FRSP (front spring) S3234 = 32mm od and 340mm/34cm length. The original spring rate might be missing on older bikes though. The same period GSXR750 has a spring rate of  .58 kg/mm - so it's likely the 1100 ran a slightly higher rate ( .68 ?) being  heavier.

Racetech are about the only people to openly print these details, been useful to me a few times.

[Racing Geek]

Yes but the FRSP S3234 is a 31.7mm OD and 340mm long. Any bike with a stock spring that's close to that OD will have that specific spring recommended for it and there's a lot of bikes that have this spring listed as a replacement. 80cc dirt bikes, cruisers, standards, sport bikes all of widely different years supposedly can run this spring. I find that hard to believe especially when the spring it recommended for one of my past bikes was much shorter than the stock spring. That's why I need measurements of the stock stuff. I'd rather not pay $130 for springs if I can get some out of junk forks for $25 and even if I was willing to pay the $130, they don't make springs soft enough for my application and the springs recommended for my bike don't come stiff enough. That's my predicament.

[Oilyspanner]

A mini moto is stacks lighter than a standard bike, specialised springs might be your only option.

[dupersunc]

I assume you're talking about a pitbike, crf150 type thing rather than a mini moto.  The forks will have a piece of tube under the springs that acts as a preload spacer.  Get the springs you want in the correct diameter and rate, then make/ modify the preload spacer to get the correct installed length. 

[Racing Geek]

"might be my only option"

Might being the key word. That's why I'm asking for stock spring dimensions.

 

Bike I have is a CR80. I'm aware of using a spacer to add preload and/or make up for spring length. I've put CL350 springs in TTR125 forks, 1960's Triumph springs in a YZ80, and manay more spring swaps in street bikes. My comment about the FSRP spring was to point out those dimensions cannot be trusted when referring to stock equipment and why I need dimensions of stock equipment.

[Racing Geek]

Anyone?