TOPIC:

Anyone know what the acceptable clutch stack height is for a KZ1000J?

It's not exactly in the same terms, but take a look at Page 3-21 in the manual at www.kzrider.com/modules/ServiceManuals/K...Service%20Manual.pdf You may be able to use that info to check your clutch thickness. Ed

The friction plates commonly last the life of the bike, but the springs don't.

My problem is the clutch doesn't disengage fully.enough. Have to put the brakes on to prevent the bike from creeping when in first with the clutch pulled in, hard shifting and hard to get neutral. This has been a problem since I got the bike, which has an aftermarket hydraulic setup, undercut trans and big block. The slave checks out, push rod, frictions and springs have been replaced. I want to try reducing the stack height, but would prefer to know what the objective is as opposed to doing it by trial and error.

Your problem is quite possibly warped steels as this is common in high power engines so these should be inspected for blueing and warpage on a flat surface (Mirror etc.)
Frictions rarely distort and any fault there usually results in slipping not drag.
The stock lift for clutch release is around 3mm and much less than around 1.5mm will cause dragging so check that the clutch master and slave are compatible and lifting enough.
Also inspect the alloy basket "fingers" for notching where the friction plate tangs sit.
These will wear over time limiting the plates movement when released and also cause your problem..
Also how would changing the stack height on a stock clutch solve your creeping issue.? (unless you are getting coil bind in the clutch springs before the clutch has fully lifted due to incorrect springs or too many preload washers in a 2 stage or multi stage set up )
The height in a stock clutch is fixed by the amount of plates and their thickness and any adjustment only relates to slipper clutches or getting a correctly balanced 2 or multistage clutch ,(lift verse grip and spring pressure) for achieving optimum performance over the 1/4 in drag racing. ..

So you don't know what the stack height should be?

The clutch had 9 frictions which were in decent shape and have been replaced with 9 new frictions, so the clutch had an extra plate kit in it. The steels are flat and of unknown origin. Frankly they look nice enough to be recent. The basket fingers are excellent. The master throws 5mm unloaded. For all I know, the basket has been modified to allow the extra plate kit or the steels are stock when they should be thinner. No steel thickness spec so can't tell and can't tell what the stack height should be. I'd like to avoid just throwing parts at this to make it work. The stack height would be a helpful clue.

If someone could help with the info that would be nice.

Take the extra plates out and see if that helps.
Steve

Yes! I know what the stock height should be and I could just go out and measure one of my spare clutch's but the stock clutch pack won't cause your issue.
However you are now saying that it isn't stock but has an extra plate so the stock height is irrelevant .
If you had suppled the correct information you would get a more helpful answer.
The extra plate kits use stock steels and thinner frictions and you have incorrectly fitted stock frictions which will preload your clutch springs and limit their movement due to possible coil bind so this is most likely the cause of the binding.
You cannot use stock frictions in an extra plate kit as the combination of an extra plain and the stock frictions risk the last friction dropping of the inner hub splines and locking the clutch and there is also a risk of the pressure plate being pushed out so far that it binds on the inside of the clutch cover creating swarf which will contaminate the oil.

You either need to buy and fit another extra plate kit (APE Trac king or Barnett etc not needed on the road) or revert back to stock be removing one plain and one friction and this will give you the stack height measurement you asked for..

It is fitted with new Barnett extra plate frictions. There are the correct number of steels for the extra plate kit. For all I know, a previous owner could have warped the Barnett steels and replaced them with stock items. The bike had an extra plate in it when I got it. I've removed a plate and friction and it slips with the new springs installed. Before I buy Barnett extra plate steels, I want to see where I'm at relative to the stack height I should have.

Just trying to avoid throwing parts at it, but if no one knows or wants to provide the requested info, I'll just throw parts at it.....

Does clutch slip in normal riding of full throttle ?
The top pressure plate needs to slip smoothly on the inner hub.
The big stack of plates can move the pressure plate to high damageing the splines on the pressure plate or inner hub.
Also check the clutch is fully released and inner rod is loose.

The clutch doesn't slip at full throttle. Clutch operates normally except for excessive drag when pulled in fully. Frankly, it works well enough that I'm pretty sure the previous owner, just avoided riding it in town. I don't find its' operation acceptable, since it has no cush drive in the rear wheel and shifts hard. Making the clutch work better will assuredly be cheaper than repairing the transmission. Hub splines look perfect. Pressure plate and bearing are good. Push rod is new and moves freely.

You knows folks I'm pretty new at this. I've only been working on bikes for 40+ years. Be nice if I could get an answer to a simple question instead of all sorts of other information that isn't helping or assumptions of idiocy like when I say it has an extra plate clutch assuming that I wouldn't know the plates in the clutch can't be stock plates for it to work. The net here is I'm trying to work on a bike which was built in 1992 with lots of modifications and little documentation and been through who knows how many owners, so I'm trying to not assume anything and instead trying to take stock of things to understand what is what. For all I know the pressure plate is modified or the clutch basket is modified. They don't look it, but I'm not familiar enough with this model engine to know by sight.

Knowing the stack height simply helps me eliminate or identify a potential reason for my problem.

I've got one or two other things to look at (for example I've haven;t measured the slave throw under pressure yet), but I'm running out of things I can look at before I assume trying new parts is going to be the path forward.

I fitted a hydraulic set up to my bike. A ZX9r to a KZ1000 engine. I matched master to slave to eliminate any problems in that area and used a stack of washers between the slave and the mounting plate to give me some adjustment down there. I could not get it to work,no matter what I tried. I replaced all the springs and plates, de-notched the basket, shortened the push rod,lengthened it again. It drove me crazy. I spent a lot of time (and money) on it but I just couldnt get it set up right. I even started suspecting the gearbox!
In the end,I reverted back to the cable set up and it was night and day. (after a new cable) it works perfectly. No creeping,no jumping,no hammering it through the gears and its so nice to be able to just snick into neutral.
I was advised later that it could be the fact that a ZXR slave dosnt push the rod far enough. Possibly not as far as needed on a KZ. A Ducati set up pushes further and might work.
I might try again with hydraulics in the future but for now Im sticking to the original cable set up.
Hope this helps

P.S. Sorry,I dont know the stack height, but if you can refit the cable set up, at least that should tell you if the clutch itself is the problem or not.