Fork spring length

[Mississippi]

Can anyone tell me what the length is of the OEM fork springs for a 78 or 79 Standard is when not compressed? My bike has Progressive springs and I think they are longer than stock. It causes the front end to not have any "sag" when I am on it. I am considering cutting these springs to correct this. The ride will be improved. Thanks

[boyat68]

Mississippi: According to the manual, page 5-13,"Check the free length of the springs."

Fork spring length:

503.5mm (19.82 in)

[Mississippi]

Thanks a lot Boy. It never dawned on me that the maintenance manual would provide this length. The Progressive springs are 20.56. The 19.82 in the book is the minimum length after use and some natural compression springs get with use so I will try to determine how much to remove from these springs. I think .250 would be a starting point since they are .740 longer than the min. length.

[TopCatGr58]

Hey Mississippi,

Aside from not having any "SAG" when you are on the bike, WHY are you wanting to cut the springs?

The progressives are one of the best handling mods you can have on your machine. Progressive only made 1 size for both the standards and specials, and the special tubes are longer, so a spacer is needed for them.

Most folks have to do some compression of the spring to be able to put the fork caps back in place.

Are you having any other handling issues, rough bumpy ride on the front end, or what???

You may know what you're doing, I don't know your level of mechanical expertise, but you are the FIRST person who has wanted to REMOVE any length from their Progressive springs!?
T.C.

[Mississippi]

Hi T.C., The springs keep the forks at full extended travel all of the time except when hitting bumps or potholes. It dosen't ride bad but I think the ride would be improved with a little sag so it is not aginst the top, extended position all of the time. I bought 2 new 78 Standards in 1979 and liked the feel of the ride with some sag. All of the top suspension "Guru's" recommend some sag front and rearfor best performance.
I have two 79 SF's and both have some sag and ride very good. I am aware of the spacer required for the Special forks.
I agree these springs are a good performance improvement.
My past experience is, I started riding in 1959 (Cushman Eagle) and have had motorcycles all of my life (I currently have 10). My past mechanical experience was automotive, worked in a Norton/Ducati shop in the mid 60's and aircraft maintenance from 1967 until I retired last year. Last job, 28 years with Beech Aircraft/Raytheon.
I think Progressive made thes springs to the "Heavy Duty" spec because a lot of people had fairings and bags which overloaded the stock springs and made the XS11 handeling issues worse. I know Yamaha also had a set of Heavy Duty springs for this purpose.
Thanks for the input,

Harold

[tarzan]

You know when you cut springs down it makes them stiffer (less give).So I doubt it will make them sag or cush.I suppose if you cut them short enough the bike will sit lower,but then the springs would be too short and would not have the compression neccessary to get them into into a dampening feel.I personally would not recommend that.

[Mississippi]

I know that shortening a spring will make them stiffer if it is a significant amount but 1/4 inch on a spring that is over 20 inches long will not have an effect that can be noticed.

[fredintoon]

There's things not to mess with

"I know that shortening a spring will make them stiffer if it is a significant amount but 1/4 inch on a spring that is over 20 inches long will not have an effect that can be noticed."
Hi Mississippi,
If removing 1/4" won't make it significantly stiffer it won't produce a noticeable sag neither. Which end you gonna crop anyway? The tight-wound or the loose?
You got the gear to taper & close the new end you are going to make?
Doing this is not a good idea.