Top-End Reassembly

You might want to try this method for measuring piston and combustion chamber volume. 
It produced adequate results for my needs without creating a mess, or robbing my piggy bank in the process.

The crude short videos below were recorded early A.M. December 9, 2025 will be available to view for a limited time.

Piston volume 21.872 cc:
photos.app.goo.gl/c9zyXeB8uDivpkVJ8

photos.app.goo.gl/gVSyfzytp9PifjSo7

Combustion chamber 44.36 cc:
photos.app.goo.gl/D4BLEwMG6XGz7eqK8

photos.app.goo.gl/f3dWPiSmRqpUdxtr8

The Omni compression ratio 10.252:1 result was based solely on measurements derived from the processes shown.

Please advise me of mistakes you may find in my calculations.


😉
 

Wookie58 wrote:

That's an interesting and ingenious way to resolve it - I guess at this point in time they are ornaments unless you want to get into a legal battle with Wiseco so what have you got to lose ?. You might want to check the weight afterwards so you can get them as close to equal as you can


 

Each Wiseco piston measures 9.2 ounces. That is, after 0.1 oz. was machined off to provide sufficient clearance...for these:



🙄   oh boy!


* Note:  The Piston Volume value is negative (-) in the Omni CR calculation.

MTC G1135-C pistons (with 3mm machined from crown) yield
10.35:1 +/- compression ratio using the same method.

 

daveo wrote:

 

Is it possible the combustion chamber volume stated in an old magazine article may be incorrect?

See paragraph seven of:

Kawasaki Gpz1100 | Cycle World | JUNE 1983 share.google/dOkqgg7lg1xvxgMNn

Early KZ900/1000 heads are 36cc and the later J type are 40cc..

zed1015 wrote:

Early KZ900/1000 heads are 36cc and the later J type are 40cc..
 

Thank you Rob!

My previous volume calculations are off by roughly twelve percent, as confirmed with a digital scale.

Consequently, the 84-85 ZN/ZX1100 cylinder head combustion chamber volume measures 39+/- cc's.

🤔


 

The cylinder image is typical of the others with 200 psi compression after one 6K mile riding season. 

Do they need honing and new rings, or should I just reuse them as they are with the old rings?


 

Can you catch your fingernail in them? I'd give them a light brush with a hone and new rings. 

With that compression and only 6k mls I would "glaze bust" it with a light hone and put it back together, shouldn't need rings (you can measure the end gaps before you re-fit)

I never reuse old rings, as if they have accrued more than a couple of hundred miles they will most likely not seal properly even in a fresh bore. I have documented this with a couple of close associates under the same circumstances a couple of different times over the last +40 years. Even with Wiseco, MTC, JE, etc.

Even though it cost more I always go with fresh rings every time I remove rings from a bore. Head gaskets are too costly now to rebuild a "smoker".

This is just my opinion so do what you will.

Ordered rings, and had the cylinders honed.

It was the wise choice...no doubt about it.

Thanks Guy'Z

Merry Christmas!
😶‍🌫️

Clayed one piston before assembly



Radial valve clearances were achieved by machining the valve pockets with a jig fixture and old Hitachi plunge router.

🧐



Thank you once again Rob!   😉