TOPIC:

Hi, hoping a knowledgeable person on this site can assist in identifying my KZ750e pistons.

I have a 1982 KZ750L2 which I bought as a non running bike.
Engine turned over by hand but hadn't run for who knows how long.

I started pulling the engine down and found it was already bored to 69mm with aftermarket pitons.
The question is what brand cast or forged and what compression ratio?

From other great posts on this site have recognizes the Wiseco oval logo under the piston.
I thought maybe cast but now thinking forged due to being wisco but the numbers don't match with current 10.5:1 pistons.

I have posted much the same on turbo750 but no one could really help.
Much appreciate anyones feedback.


Wiseco logo...


Dirty piton on engine. Note the dome which measure about 6.5mm or 1/4"


same piston after lots of cleaning...

Any help and feedback would be much appreciated.

I have a really good idea of what they are but since you did not upload your pics I can not verify what they are.


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Thanks Nebr_Rex, attached the images. They show up in my preview but not in the post. Every forum is different, sorry still learning this one.

You have an older Wiseco big bore KZ750 piston.
The newer pistons have the part number lazer etched into the top like this.


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If that is a “C” stamped on top, then you have, as others have noted, a vintage design of pistons Wiseco no longer makes. There may be a chance you will have to have custom rings made for these pistons as Wiseco no longer supplies them.

This thread 2008 may provide more background on what you have.

kzrider.com/forum/2-engine/235655-c-on-top-of-o-s-pistons

Thanks guys. I had read the linked topic on wiseco rings and along with the logo figured the pistons were definitely wiseco, but the lack of info on the part numbers had me confused. Does anyone know what compression ratios were offered in the old range? Only offerings now are the 10.25:1 and 8:1. The part numbers on my pistons are partially missing as the gudgeon pin oil hole has been drilled and debuted overtop of the numbers. The part number starts with a 4 and ends with a 3. See pic.