Dual-Rate Fork Spring Kit

[terribletabo1]

Has anyone tried these Dual-Rate Fork Spring Kit:

I contacted them but they replied:

Wendon't list the XS650 but it may be the same as the 1977 XS850E/F if you can confirm it. The kit for the 850 is #FK280X

I was originally going to get the springs & emulator from Race-Tech until I stumbled onto this. It sounds like a good idea for my Scrambler project.

[tomterrific]

I'd go all the way with the emulator valves. The valves are a leap in damping and if set up they should offer fiork action better than anything you can get otherwise.

TomGraham

[xsleo]

I think the XS850 used larger diameter tube size. 36 or 37 mm so those springs won't work.
If you want to use that kit, get a 77 XS850 E/F front fork. You will need the trees too. The stem length is shorter so you will need to swap stems.
I replaced my springs with a set from J&P Cycle their item number 230-584 $44.95 They fit older Harley's that use a Showa 35 mm fork. They are wound from a larger diameter wire, and a bit longer. So they are stronger. These are a straight rate spring.
I did the Minton mods as far as drilling out the holes in the damper rod. Not adding any. Works very well.
These springs will work well with the Emulators. you might have to shorten them if you can't get enough sag with the emulators. I have them in a 79 set of forks with the adjustable caps. On the first setting I get about 25 mm sag, on the second setting I get about 12 mm sag.
I plan on trying the emulators, I have a set of the nonadjustable caps that I can use if the adjustable caps won't work out.
I might suggest trying them with the holes drilled out on the dampers as Minton suggests then try several oil weights to adjust the damping rate.
I use ATF at 6 inches down from the top with the springs out, forks collapsed. I have tried several oils, 5w20 and 10w30 engine oils and the ATF. so far the ATF feels good.
Using the 6 inch down oil level is about 7.5 to 7.75 ounces of oil. This is more than the stock oil amount of around 6 ounces but this helps limit fork dive while braking.
Leo

[terribletabo1]

Thanks for all the advice.

[grizld1]

Leo, be advised that shortening a spring will increase the rate of the spring in direct proportion to reduction of length; i.e., 10% reduction in length produces 10% increase in rate. Shortening springs is not a good way to increase sag. Fork springs need at least 1/2" of preload, and at the end of the day you could wind up with insufficient sag.

[xsleo]

I do have a set of the flat non adjustable caps I can use. Those should give me enough space to add a spacer even with the longer springs.
As I remeber the stock springs, with the forks extended, were about an inch below the top of the forks.
The new springs were just a bit below the top of the tubes, maybe 1/8 or so.
So with the Emulators and the flat caps they will be ok, or need some spacer.
I'll know when I get that far.
I also have a set of the 37 mm XS1100 forks I want to try. They use a shorter offset of stem to fork tubes than the XS650, as well as a shorter stem. I have an extra set of trees off a 79 XS650 that I can swap the stems to use the XS1100 forks.
It will be awhile before I get there but I'll let people know how things work out.
Leo