Fork Issues - worn piston?

My 78 KZ1000 has been feeling a bit weird in the handling department for some time. . . .getting worse all the time.

I think I've narrowed it down to bad suspension, as the forks feel like pogo sticks now.

I changed the oil (had some pretty nasty stuff in there (about 9K since they were rebuilt and no changes since). But it still handled weird.

I took the forks apart and was trying to get my head around how the valves and passages work for dampening (which mine seem to have none of). It appears that the cylinder needs to make good contact to the outside inside of the inside fork tube in order to create a chamber where pressure can build up and dampen.

It seems like the the cylinders have a little bit of play and are not running smooth against the inside of the tubes, thus allowing oil to leak by. I'm going to try 20w and see if that helps.

Sound like a reasonable approach?

Later model Kawasaki's (like the 83 GPz750) have bushings in the lower fork tubes that can be replaced, but your bike (like all the other KZ models) has the upper tubes riding directly on the aluminum of the lower tubes.
The easiest solution (if that is the problem) is a good used set of lower fork tubes.

Steell, I think he's referring to the part that goes inside the inner fork tube: Kawasaki part #44022-1002 CYLINDER-FORK, item 26 on the diagram.

Precisely guitargeek. That cylinder has an opening through the middle that would let tons of oil flowing through (providing now dampening)

The top ring of the cylinder should seal against the fork innertube as it slides upward, and create a small chamber along the outside of the cylinder. This is where the dampening happens (I think).

When I put the cylinder into the fork lower tube, I can wiggle it a little bit.

I'm hoping that 20w will work better. I started thinking about it and remembered that on some of my testrides before, it seemed okay at first and got bad after riding awhile. That would make sense if the oil is warming up a bit and passing by the seal more easily.

I am running a temperature of 102 right now (my body, not my bike), so unfortunately, I can't really work on it right now.

Damn, dude! Feel better soon...