TOPIC:

YES , think the ez way to explain is imagine the spring uncoiled in a straight bar form.Say just for numbers it is 6'long and takes 1 lb, to deflect 6" it then cut 1'off and it well 1.5 lb, to deflect the same 6"

Not knowing all the dimensions of the spring . you measured it at 6lb what % of the overall length is 10mm? sure that there is a formula to figure out I do agree that the chain would not be affected by the change of spring rate

This is interesting

I can visualize how a spring with less material will have a different spring rate or stiffness compared to one with more material. Although the spring rate wouldn't matter when it comes to what this particular spring is being used for.

I'd like to hear all the angles as well. The issue with the springs we are having is the strength and pressure that the spring puts on the tensioner arm tends to eat it up much quicker. The solution from another forum was to shorten it and that seemed to work for others although I have little personal experience with it since I have a manual one myself.

I'm trying to visualize how this will affect the tensioner's effective range of operation and overall pressure. When material gets removed from it, I'm thinking this would reduce the pressure being applied to the pushrod at the expense of how far out the pushrod can go. If the spring is already more than long enough to compensate, then this wouldn't be an issue but I wanted to bring it up in case noone's thought of it . You could stretch the spring after cutting it to make up for the lost material as well.

Would be interesting to see if anyone's tried using other springs as well.

This wouldn't even be an issue if we can get a metal cam chain gear. I wonder when those will be done? lol

I have not, as yet, changed my tensioner ( the bike will be undergoing extensive renovation soon ) so this suggestion might be nonsensical, but can the original 1300 spring be used with the ZX11 tensioner? If not, how about trying to source a spring of suitable rate to fit the ZX11 tensioner? I must say, I have had my doubts about simply shortening the ZX11 spring, as it is sure to have some adverse effect, such as has been suggested, ie force exerted over range of travel.

OK,

The spring for both tensioners is completely different & cannot be interchanged.

Here is 15 years of 1300/6 camchain tensioner exchange experience (I used manual tensioners before that on the other 5 bikes).

1). When the ZX11 tensioner is used with the FULL LENGTH SPRING, the black rubber roller on the tensioner arm wears down in around 15000 to 20000 miles & the chain expands noticeably (STRETCHES) in size.

2). When the spring is cut 10mm shorter............the black rubber roller DOES NOT wear away at any rate noticeable & chain shows no more signs of wear.

3). All of this tested & proven with may last 6 Z1300's & 3 close friends bikes too.

Conclusion.
If you dont want to cut the spring 10mm, just allocate enough money for a top end strip & rebuild every 20,000 miles or so.

I ONLY GIVE ADVICE AFTER YEARS OF EXPERIENCE & TESTING MYSELF ON MY OWN BIKES........NOT JUST FOR A LAUGH.
IF YOU DONT WANT TO TAKE THE ADVICE, JUST DO WHAT YOU THINK IS BEST & IGNORE ME !


Simple

Pete F

If you have a 20 inch spring with 40 coils and a 20 inch with 30 coils the one with 30 coils will be a stiffer spring. However if you cut 10 coils from the 40 coil spring the spring will be shorter so a true comparison cant be made. To compress both the shortened spring and the normal 20 inch 40 coil 6 inches the shortened spring will take more weight to do that 6 inch compression because you are effectively using the same weight as you would need to compress the 40 coil spring 8 inches..
Here are a couple of sites that may help a bit better than I can explain.


enpub.fulton.asu.edu/imtl/HTML/Projects/spring_report.pdf
springipedia.com/compression-general-design.asp