kz650 Stiffer Fork Springs

More. All Good info. Running heavier weight fork oil slows both comression and rebound speed via damping valve. using more (I wouldn't add more than @ 10 %)tends to lessen bottoming. Pre-loading increases initial ride height. progressive springs increase in resistance as springs compress due to different spring wind and diameters. You can stiffen constant rate springs simply by shortening(cutting) and replacing the diffence w/ spacers. if you do this, start slow, the difference is logrithmic.if replacing springs, try to retain stock outside dia,'s as springs grow slightly when compressed and can jam in bores. hope this helps g

KawiConvert wrote:

I am looking to stiffen up the front a little....

If not alreay done, could also try using ATF with existing springs and set-up.

Good Luck!

yeah on the air caps...i know the fork cap you have and don 't know if there is sets kicking around...i got a clean gold aluminnum set off e-bay for a decent price and they look cool too...900 though....have not looked at em much for smaller cc bikes....try asking redline cycles they came used from them on e-bay they say they have all kinda stuff..i think 17 -27 cant for mine cant remember now..i only put 9 p.s.i in each but it is big dif

Patton, ATF has some cool attributes, one of which is it's cleasing tendancy. Honda (I know dirty word) used it for many bikes for years because it resists foaming. unfortunatly it's usually about a 5w. and valving was set accordingly. Thoughts? G

650ed has a good point. Make sure your seals are good first. It's just a few bucks and might solve your problem outright.

I went through the same thing last year, threw down the cash for the progressive springs and found that my springs were fine, and the seals were the main culprit. I ran 30w motor oil in them and this year I'm draining them and going to a lighter weight for the sake of my poor wrists.

I don't think you would want them any stiffer than mine are right now. For serious. :blink:

The original 1973 Z1 Owner's Manual specifies 10 wt motor oil. Back then with my new 1973 Z1, one of the mods being suggested by the magazine testers was using ATF to stiffen the front suspension which supposedly enhanced the handling. Many "experts" were condemning the oem fork oil as "fish" oil.

I don't recall the viscosity rating of the ATF involved, and don't know whether ATF weight rating is directly comparable with motor oil weight ratings.

However, as suggested in the magazine articles, I did indeed experiment with using ATF in the forks instead of the factory recommended 10 wt motor oil, and recall the front suspension did feel stiffer with the ATF.

But desiring a softer cushier more comfortable front-end suspension for long distance cross-country riding, I soon installed progressive springs and started experimenting with various weights of design specific "fork" oils.

Same as above with the 1976 KZ900-B1 LTD (where FSM specifies 10 wt motor oil, non detergent).

Still using progressive springs in both bikes and continue to goof around with the various fork oil alternatives. :lol:

Good Luck!

I had air caps on my 1000 and took them off. They worked real good until they leaked down which would take about 2 days. I bought a set of progressive springs and am very happy with them.

On my kz1000 if the air pressure drops to around 20 psi or below on the front tire the steering becomes almost dangerous.

Well, for a little more background on the bike, the tires, oil, seals, and bearings (wheel and steering) all have about 300 miles on them. The springs I assume are stock and have about 17K miles on them. I keep the front tire aired. My fork seals are good so I am mainly looking at the springs or some other preload/damping adjustments that I can make. Though I do appreciate the other ideas as that helps me to look at what may be wrong.

One thing I am looking at are some springs from a gs1000 that uses the same springs as my KZ according to the progressive site. Does anyone know if it would be a bad thing if I cut off about 1-2" of spring and used a fender washer to stack it on my stock springs like the PVC but with the extra spring? I am wondering how well this would work or if anyone has tried it before.

If not already done, would remove and examine the fork springs to see if by chance they are progressive replacements. There are of course varying size spaces between the coils on the progressives vs. more evenly spaced coils on oem springs.

Am thinking it may not be worth the effort to cut a short section from another spring to install instead of using a simple spacer.

Good Luck.

Well, simple may not be the way to describe it. If I do a spacer, I'll turn the appropriate size spacer out of aluminum to make sure I get the right diameter. Thanks for the advice, the springs were about 20.00 and the spacers will be a lot easier and cheaper. Also, the springs are not progressive, when I had them out a few months ago I noticed that the coils and turns are constant like the stock single rate ones. Thats one of the reason's that I think they are stock, nothing extraordinary about them, and the previous owner didn't strike me as the kind to change out the springs. I'll have to pull the top off this weekend and measure the tubes and springs to size my spacers.

Would these help?

l0g1c wrote:

Would these help?

Possibly. I need to measure my springs to check and make sure.