Air Assist shocks? or not...

I'm replacing the forks on my '80 KZ550A1. I'm looking at a set of '82 KZ650 forks that should fit as long as I get the matching caliper and rotor. The 650 forks are the "air assist" style, with the air fitting at the top of the fork tube. What's the general consensus on these? Any reason to avoid them?
thanks!

You can get them and install progressive springs or keep the ones you have, do the same thing.
Steve

When you say keep the ones I have, you mean keep the springs I have and use them in the KZ650 forks?
I already have the KZ650 fork lowers, do you suppose I could use my stock KZ550 fork tubes in them?

swest wrote: You can get them and install progressive springs or keep the ones you have, do the same thing.
Steve

The internals of the 1982 KZ650 forks are different than those of the 1980 KZ550 forks, so I suspect trying to mix parts between the two different types of forks is a bad idea. Ed

I have all the original internals for the 650 forks including springs, everything except tubes.

650ed wrote: The internals of the 1982 KZ650 forks are different than those of the 1980 KZ550 forks, so I suspect trying to mix parts between the two different types of forks is a bad idea. Ed

I was suggesting you can keep the 550 forks and put in progressive springs.
Steve

carwash wrote: I have all the original internals for the 650 forks including springs, everything except tubes.

650ed wrote: The internals of the 1982 KZ650 forks are different than those of the 1980 KZ550 forks, so I suspect trying to mix parts between the two different types of forks is a bad idea. Ed

If you plan to use those KZ650 fork parts you should acquire the tubes. Ed

Why do you want to replace you current forks? Usually, folks switch to much newer forks to take advantage of developments in ride, handling and braking. I doubt if those old 650 forks will provide any improvement worth the headaches.

650ed wrote:

carwash wrote: I have all the original internals for the 650 forks including springs, everything except tubes.

650ed wrote: The internals of the 1982 KZ650 forks are different than those of the 1980 KZ550 forks, so I suspect trying to mix parts between the two different types of forks is a bad idea. Ed

If you plan to use those KZ650 fork parts you should acquire the tubes. Ed

And finding used tubes is not super easy. I replaced one of mine a while ago which was dented from the the triple tree having been tightened just a little too much. I hadn't even noticed, until I tried to install the progressive springs I picked up to beef up the front suspension a little. They were ever so slight larger, and the tiny dent wouldn't allow them to seat well and move freely.

Anyway.... you can risk buying used tubes and hope they are not pitted or bent, or new ones are available, but last time I checked they were something like $120/each. Generally, i would agree with the above opinions. Get some upgraded springs for your current shocks, and if you want to spend some money, go with emulators as well. I was very pleasantly surprised with the difference a set of progressive springs made in my bike. (I also replaced the rear shocks/springs at the same time, which balances out the handling beautifully.) There are certainly better, more expensive options out there but unless you happen to come across some ohlins or marzocchis (etc) on the cheap, or want to swap in a modern front end with all the attendant modification that goes along with it..... you may be really happy with upgraded stock parts.

Cheers!
Jon

I bought new fork tubes at Z1E. About $80 for the pair.
Steve

Worth writing them to ask about tubes for the 550 or 650 then. They are obsolete from Kawasaki, and that was the quote I got, but it was a while ago. The guys at Z1 Enterprises do seem to be able to find most anything...

I've been told you can swap in tubes from some 900/1000's to lower the front end a little, but I don't know if you want to start messing with geometry.

Good luck with whatever you choose in any case. Post some photos of the bike!

Cheers,
Jon

I've completely gone down the rabbit hole on this. My desire for replacing the forks is aesthetics, not performance. The '80 KZ550 has the short, black, fork lowers, and the look just bugs me. I want the longer lowers, in silver. If I could keep everything on the stock front end and only replace the lowers I would, but it looks like that's not possible. At first i thought I could just get a different set of forks, but then found out the caliper mount is different, then realized the rotor is a different diameter, and the 1980 front mag has the larger rotor attached with the four bolts instead of the seven bolt attachment that came the next year, so I can't really replace the rotor on this wheel with anything that would be compatible with any other early 80's KZ forks.
So after all that I thought maybe replace the entire front end, not as extreme or expensive as it sounds.
I've got a lead on an entire '81 KZ1100 front end in perfect condition, forks, rotors, calipers, triples, wheel, all I would need would be the conversion steering stem bearings. I could get all this for just over $200.
My current stock set up needs new fork seals, a caliper rebuild, new tire, and I'd like to powder coat the wheel, and/or powder coat or strip the lower.. So most of the labor is happening anyway. I figure if I'm going to swap anything out, now's the time to do it instead of putting time and money into my current set up.
With the KZ1100 I get everything I want and more. Longer, silver fork lowers, and slightly larger (diameter) fork tubes, which would be kinda nice. My main issue at this point is I don't really understand the "air assist" forks. Can that be bypassed? Can you just get standard caps for the fork tubes and not use the air assist?
Anyhow, again, I know it sounds extreme, but replacing the entire front end would be less than $200 if I recouped even a little by selling my stock front end.

Or I could just leave it alone.