Timing chain idler question

How much slack is the top idler supposed to have?
I looked up a new one just incase and couldn't believe what they cost.

The top idle should not have any play (up and down) but a little play left and right is okay.
The rubber parts of the top idler sprocket get brittle over decades an can be disintergrate of the bearing and sproket body!!!!

Non of the idlers should have any slack.
There is a very small amount of side clearance where it can slide on the shaft but nothing else.
These idlers have a rubber inner ring bonded between the sprocket ring and inner steel that holds the needle roller bearing.
The rubber hardens over time and becomes unbonded from the center allowing the separate parts to move independently then eventually collapse.
The technical term for this is " knackered" and you will need to replace it.
You could go OEM but they are expensive and will go the same way eventually or buy a solid type made by LISKA and PMC etc which does away with the rubber and is just a solid steel sprocket with the needle roller in the center..
I would go for the solid type. They are cheaper and will out last the bike.
Some say they run a noisier then stock but I have them in all my engines and you can't tell the difference.

As zed1015 explain take a look on this thread.

kzrider.com/forum/2-engine/611047-z1-cam...ssy-sprockets#807393

I had a whine in my engine that I thought was the top idler. So I purchased a new one (OEM) and installed it but the whine was still there. After riding season I took the head off and found what you see in the photos below.

I did a deeper dive into the engine and everything was fine. The idler that sits on top of the cases was in good shape. The chain was within the spec but I replaced it anyway because the cases were split.

The front rubber idler was somewhat chewed up from the chain over the last 44 years.


Side view of the front rubber idler shows cracks in the rubber


The rear idler had separated inside and I believe was the cause of the noise.


Closer view of the separated idler.

For Bulletkz...the box is heading your way.

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The idler looks alot like this one from a 92 Suzuki. If the teeth are the same ,For $20.00 I might try it.
I can't believe that a oem Kawasaki idler sells for almost $200.00 . 1/2 the price and you can get a aftermarket one that last forever.

'92 Suzuki what? Please let the forum know if you try this & what the results are.

Good Ridin'
slmjim & Z1BEBE

Not sure about the yeas , looks like Suzuki used it from the 80s into the 90s.
The one I found is from a 92 katana 750.
It doesn't seem to have the rubber and looks beefier.
If the bolt holes line up and the gear is the same, that would be great.
Would also mean the Kawasaki parts are very overpriced .

I don't think there is any question that Kawasaki Z and early KZ parts are over priced. It didn't take long for me to figure this out when rebuilding my KZ-1000. If a new part has a direct application to one of those bikes the price goes up substantially and as these parts become less available the price goes up even more. The jayhawkers on the "for sale" sites know this and have no qualms about jacking up their prices. It's a sellers market in many cases.

Rick H.

Bulletkz wrote: If the bolt holes line up and the gear is the same, that would be great .

It's not just about the tooth pitch and mount holes. The sprocket diameter and or the axle height from the head needs to be the same also.
Too high and the chain will be loose between the cams and alter cam timing and it'll rattle, too low and it will over tension the cam chain and knacker it very quickly. Which would you rather a few dollars more for the correct part or replacing the chain with associated costs and engine out and split grief?